Acute Hepatitis C Virus Infection

Infectious Disease MONDO:0100371 Pathograph 21 Show in embeddings browser Acute disease Hepatitis C virus infection

Acute hepatitis C virus infection is the early phase after acquisition of hepatitis C virus (HCV), before either spontaneous viral clearance or persistent infection is established. The course is often clinically silent; symptomatic hepatitis can include jaundice, nausea, fatigue, anorexia, and elevated hepatic transaminases. Diagnosis requires both evidence of current infection and evidence that acquisition was recent because anti-HCV and HCV RNA results considered at a single time point do not reliably separate acute from chronic infection. Early direct-acting antiviral therapy can eradicate viremia and prevent chronic infection.

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12
Pathophys.
5
Phenotypes
2
Hypotheses
3
Gaps
21
Pathograph
1
Genes
2
Medical Actions
2
Differentials
3
Datasets
1
Trials
2
Deep Research
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Classifications

Harrison's Part
INFECTIOUS DISEASES GASTROINTESTINAL
◈

Mechanistic Hypotheses

2
Host-virus response balance determines clearance or persistence
canonical_acute_hcv_clearance_persistence_model CANONICAL
Evidence balance 1 support
Productive hepatocyte infection generates viremia and innate antiviral activation while HCV simultaneously suppresses interferon induction. Adaptive immune responses can accompany clearance, but ongoing immune responses and viral escape can coexist with persistence. Hepatocellular injury is immune-associated, although the contribution of individual cell populations is not fully resolved.
Pathograph links
HCV attachment and hepatocyte entry -> HCV Polyprotein Translation INDIRECT KNOWN INTERMEDIATES Productive hepatocyte entry and genome release permit translation of the HCV polyprotein. Intermediates: Endosomal fusion and release of the positive-sense viral RNA genome
HCV Polyprotein Translation -> HCV NS3/4A-Dependent Processing of the Nonstructural Polyprotein DIRECT The viral NS3/4A serine protease cleaves defined sites in the nonstructural region of the HCV polyprotein.
HCV NS3/4A-Dependent Processing of the Nonstructural Polyprotein -> HCV genome replication and early viremia INDIRECT KNOWN INTERMEDIATES NS3/4A-dependent processing releases nonstructural proteins required for HCV genome replication. Intermediates: Release of processed HCV nonstructural proteins; Assembly of the HCV replication complex
HCV NS3/4A-Dependent Processing of the Nonstructural Polyprotein -> NS3/4A-mediated innate immune evasion INDIRECT KNOWN INTERMEDIATES Processed active NS3/4A also cleaves the host innate-sensing adaptors MAVS and TRIF, suppressing interferon induction. Intermediates: Release and assembly of the active NS3/4A protease complex
HCV genome replication and early viremia -> Interferon-driven innate and NK-cell activation INDIRECT KNOWN INTERMEDIATES Acute HCV infection is accompanied by a transient type-I-interferon-imprinted activated NK-cell population. Intermediates: Viral RNA sensing and type I interferon induction
HCV genome replication and early viremia -> Immune-associated hepatocellular injury UNKNOWN Acute HCV viremia is associated with inflammatory immune activation and hepatocellular injury, but the exact direction and cell-specific causal contribution remain unresolved.
Interferon-driven innate and NK-cell activation -> HCV-specific adaptive immune response UNKNOWN Early interferon-associated innate activation precedes the later adaptive response associated with control or persistence, but the cited temporal pattern does not establish that NK-cell activation causes the adaptive response.
NS3/4A-mediated innate immune evasion -> Persistent HCV viremia UNKNOWN Suppressed interferon induction and escape from immune recognition are proposed contributors to failure of viral clearance, but their specific causal contribution to persistence is not isolated by the cited review.
HCV-specific adaptive immune response -> Spontaneous viral clearance UNKNOWN Early multispecific T-cell responses and low viral diversity are associated with untreated clearance, without establishing that the measured response is independently causal.
HCV-specific adaptive immune response -> Immune-associated hepatocellular injury UNKNOWN Activated immune-cell populations track with biochemical hepatitis, but their causal contribution to hepatocyte killing remains unresolved.
HCV-specific adaptive immune response -> Persistent HCV viremia INDIRECT KNOWN INTERMEDIATES Adaptive responses can remain ongoing yet fail to clear immune-escape variants. Intermediates: Incomplete effector control; Viral escape from antibody and T-cell recognition
IFNL3 rs12979860 host-clearance modifier -> Spontaneous viral clearance UNKNOWN rs12979860 C/C is associated with spontaneous HCV clearance, while the molecular intermediates and causal mechanism remain unresolved.
Persistent HCV viremia -> Chronic hepatitis C virus infection DIRECT Viremia persisting beyond six months meets the definition of chronic HCV infection.
Immune-associated hepatocellular injury -> Elevated hepatic transaminases DIRECT Hepatocellular injury is reflected by increased circulating ALT and other hepatic transaminases.
Immune-associated hepatocellular injury -> Jaundice INDIRECT KNOWN INTERMEDIATES Clinically apparent acute hepatitis can impair bilirubin handling and present with jaundice. Intermediates: Hepatocellular dysfunction and impaired bilirubin handling
Immune-associated hepatocellular injury -> Nausea INDIRECT UNKNOWN INTERMEDIATES Symptomatic acute hepatitis can include nausea through incompletely resolved systemic and gastrointestinal intermediates.
Immune-associated hepatocellular injury -> Fatigue INDIRECT UNKNOWN INTERMEDIATES Symptomatic acute hepatitis can include fatigue through incompletely resolved systemic inflammatory intermediates.
Immune-associated hepatocellular injury -> Anorexia INDIRECT UNKNOWN INTERMEDIATES Symptomatic acute hepatitis can include loss of appetite through incompletely resolved systemic and gastrointestinal intermediates.
Show evidence (1 reference)
PMID:25443342 SUPPORT Other
"Elimination of HCV during acute infection correlates with a rapid induction of innate, especially interferon (IFN) induced genes, and a delayed induction of adaptive immune responses."
This review supports the canonical coordination of innate and adaptive responses in acute-HCV outcome.
Intrahepatic Tfh1-like CD4 response as a helper axis for HCV control
intrahepatic_tfh1_helper_refinement EMERGING
Evidence balance 1 support
A recent chimpanzee study proposes that liver-enriched HCV-specific PD-1-high ICOS-high Tfh1-like CD4 cells help B-cell and CD8-cell responses at the site of replication. This refines the general adaptive-response node but is not asserted as a confirmed human mechanism.
Pathograph links
HCV-specific adaptive immune response -> Spontaneous viral clearance UNKNOWN Early multispecific T-cell responses and low viral diversity are associated with untreated clearance, without establishing that the measured response is independently causal.
HCV-specific adaptive immune response -> Immune-associated hepatocellular injury UNKNOWN Activated immune-cell populations track with biochemical hepatitis, but their causal contribution to hepatocyte killing remains unresolved.
Show evidence (1 reference)
PMID:40956619 SUPPORT Model Organism
"HCV-specific PD-1hiICOShi CD4+ Tfh1-like cells were enriched in liver, suggesting the potential for B and CD8+ T cell help at the site of virus replication."
The chimpanzee study directly supports the proposed helper-cell refinement while not establishing it in humans.
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Discussions and Knowledge Gaps

3
Does the liver-enriched PD-1-high ICOS-high Tfh1-like CD4 response observed in HCV-infected chimpanzees mark or mechanistically assist viral control in humans with acute HCV?
HUMAN MODEL MISMATCH OPEN human_validation_of_tfh1_helper_axis
Attached to
pathophysiology#HCV-specific adaptive immune response pathophysiology#Spontaneous viral clearance
The chimpanzee study temporally links the population to viral control, seroconversion, and hepatitis and shows enrichment in liver, but the source does not establish the same population or a causal helper function in humans. Human longitudinal sampling with matched blood and liver-proximal material is needed before promoting this refinement to the canonical model.
Show evidence (1 reference)
PMID:40956619 SUPPORT Model Organism
"HCV-specific PD-1hiICOShi CD4+ Tfh1-like cells were enriched in liver, suggesting the potential for B and CD8+ T cell help at the site of virus replication."
This is the model-organism observation whose human generalizability remains open.
Which immune-cell populations directly cause hepatocyte injury during acute HCV, and which are biomarkers or bystanders of the same inflammatory state?
KNOWLEDGE GAP OPEN cell_specific_cause_of_acute_hcv_liver_injury
Attached to
pathophysiology#Immune-associated hepatocellular injury phenotypes#Elevated hepatic transaminases
Human iNKT activation correlates with ALT, but the study explicitly cannot determine whether iNKT cells kill hepatocytes or respond to injury-related drivers. The pathograph therefore retains UNKNOWN causal directness rather than encoding a specific effector population as established.
Show evidence (1 reference)
PMID:34905514 SUPPORT Human Clinical
"Given the correlative nature of our study, we cannot distinguish whether iNKT cell activation contributes to hepatocyte killing or whether ALT elevation"
The authors directly identify the unresolved causal direction captured by this discussion.
Which early virologic and immune measurements robustly predict spontaneous clearance across populations, coinfection states, and HCV genotypes?
KNOWLEDGE GAP OPEN generalizable_predictors_of_spontaneous_clearance
Attached to
pathophysiology#HCV-specific adaptive immune response pathophysiology#Spontaneous viral clearance progression#Spontaneous viral clearance
Rapid viral-load decline and strong T-cell responses predicted clearance in an HIV-positive male cohort, while clearance proportions vary across cohorts. External validation is needed before these associations can be treated as universal decision rules.
Show evidence (1 reference)
PMID:21139063 SUPPORT Human Clinical
"Spontaneous clearance of acute HCV in HIV-positive men can be predicted by a rapid decline in viral load, high CD4 count, elevated bilirubin and ALT, and is associated with low viral diversity and strong T cell responses."
This directly supports candidate predictors while the cohort restriction motivates the generalizability gap.
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Pathophysiology

12
HCV attachment and hepatocyte entry
HCV first attaches to cell-surface proteoglycans, SR-BI, and CD81, then uses the tight-junction proteins claudin-1 and occludin and clathrin-mediated endocytosis to enter human liver cells.
Host-virus response balance determines clearance or persistence
hepatocyte CL:0000182 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hepatocyte (CL:0000182). CL:0000182 is a cell type from the Cell Ontology.
symbiont entry into host cell GO:0046718 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased symbiont entry into host cell (GO:0046718). GO:0046718 is a biological process from the Gene Ontology. ↑ INCREASED
liver UBERON:0002107 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in liver (UBERON:0002107). UBERON:0002107 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
HCV Polyprotein Translation Productive hepatocyte entry and genome release permit translation of the HCV polyprotein. Host-virus response balance determines clearance or persistence
Show evidence (1 reference)
PMID:31427285 SUPPORT Other
"The virus initially attaches to surface proteoglycans, lipid receptors such as the scavenger receptor BI (SR-BI), and to the tetraspanin CD81. After lateral translocation of virions to tight junctions, claudin-1 (CLDN1) and occludin (OCLN) are essential for entry."
This review directly supports the host-factor sequence in the entry node.
HCV Polyprotein Translation
The positive-sense HCV RNA genome is translated as a single long polyprotein in infected hepatocytes. Host and viral proteases subsequently process this precursor into structural and nonstructural proteins.
Host-virus response balance determines clearance or persistence
hepatocyte CL:0000182 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hepatocyte (CL:0000182). CL:0000182 is a cell type from the Cell Ontology.
Viral Gene Expression GO:0019080 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased Viral Gene Expression (GO:0019080). GO:0019080 is a biological process from the Gene Ontology. ↑ INCREASED
liver UBERON:0002107 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in liver (UBERON:0002107). UBERON:0002107 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
HCV NS3/4A-Dependent Processing of the Nonstructural Polyprotein The viral NS3/4A serine protease cleaves defined sites in the nonstructural region of the HCV polyprotein. Host-virus response balance determines clearance or persistence
Show evidence (1 reference)
PMID:22558217 SUPPORT In Vitro
"The hepatitis C virus (HCV) genome encodes a long polyprotein, which is processed by host cell and viral proteases to the individual structural and non-structural (NS) proteins."
The primary cleavage-assay study establishes the HCV polyprotein precursor and its processing into individual viral proteins.
HCV NS3/4A-Dependent Processing of the Nonstructural Polyprotein
HCV NS3/4A is a virus-encoded serine protease complex that cleaves four defined junctions in the nonstructural region of the HCV polyprotein. This processing is essential for viral replication and produces active viral proteins, including NS3/4A itself. The active protease can also cleave host innate-sensing adaptors, a distinct downstream immune-evasion effect.
Host-virus response balance determines clearance or persistence
hepatocyte CL:0000182 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hepatocyte (CL:0000182). CL:0000182 is a cell type from the Cell Ontology.
Viral Protein Processing GO:0019082 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased Viral Protein Processing (GO:0019082). GO:0019082 is a biological process from the Gene Ontology. ↑ INCREASED
Peptidase Activity GO:0008233 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves Peptidase Activity (GO:0008233). GO:0008233 is a molecular function from the Gene Ontology.
liver UBERON:0002107 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in liver (UBERON:0002107). UBERON:0002107 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
HCV genome replication and early viremia NS3/4A-dependent processing releases nonstructural proteins required for HCV genome replication. Host-virus response balance determines clearance or persistence
NS3/4A-mediated innate immune evasion Processed active NS3/4A also cleaves the host innate-sensing adaptors MAVS and TRIF, suppressing interferon induction. Host-virus response balance determines clearance or persistence
Show evidence (2 references)
PMID:22558217 SUPPORT In Vitro
"NS3/4A cleaves the polyprotein sequence at four specific regions."
The primary cleavage-assay study directly establishes four specific NS3/4A-dependent polyprotein cleavage regions.
PMID:22558217 SUPPORT In Vitro
"NS3/4A is essential for viral replication and has been considered an attractive drug target."
The study directly links NS3/4A activity to viral replication and its therapeutic vulnerability.
HCV genome replication and early viremia
Processed HCV nonstructural proteins assemble the replication complex that synthesizes viral RNA in infected hepatocytes, producing the circulating HCV RNA that marks productive acute infection. In one tertiary-center cohort, RNA was detectable at presentation in 26 of 30 patients; this cohort proportion is not assigned as a universal frequency.
Host-virus response balance determines clearance or persistence
hepatocyte CL:0000182 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hepatocyte (CL:0000182). CL:0000182 is a cell type from the Cell Ontology.
Viral RNA Genome Replication GO:0039694 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased Viral RNA Genome Replication (GO:0039694). GO:0039694 is a biological process from the Gene Ontology. ↑ INCREASED
liver UBERON:0002107 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in liver (UBERON:0002107). UBERON:0002107 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Interferon-driven innate and NK-cell activation Acute HCV infection is accompanied by a transient type-I-interferon-imprinted activated NK-cell population. Host-virus response balance determines clearance or persistence
Immune-associated hepatocellular injury Acute HCV viremia is associated with inflammatory immune activation and hepatocellular injury, but the exact direction and cell-specific causal contribution remain unresolved. Host-virus response balance determines clearance or persistence
Show evidence (1 reference)
PMID:23481134 SUPPORT Human Clinical
"HCV-ribonucleic acid (RNA) was detectable at presentation in 26 (86.7%) patients."
This acute-HCV cohort directly documents early detectable viremia.
Interferon-driven innate and NK-cell activation
During acute HCV, a highly activated NK-cell subset shows a strong type I interferon imprint and largely returns toward baseline after viral clearance.
Host-virus response balance determines clearance or persistence
natural killer cell CL:0000623 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves natural killer cell (CL:0000623). CL:0000623 is a cell type from the Cell Ontology.
natural killer cell activation GO:0030101 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased natural killer cell activation (GO:0030101). GO:0030101 is a biological process from the Gene Ontology. ↑ INCREASED type I interferon-mediated signaling pathway GO:0060337 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased type I interferon-mediated signaling pathway (GO:0060337). GO:0060337 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
HCV-specific adaptive immune response Early interferon-associated innate activation precedes the later adaptive response associated with control or persistence, but the cited temporal pattern does not establish that NK-cell activation causes the adaptive response. Host-virus response balance determines clearance or persistence
Show evidence (1 reference)
PMID:41453396 SUPPORT Human Clinical
"Collectively, these data suggest an interferon-driven rise of an activated NK cell population during acute hepatitis C that is largely restored upon viral clearance."
This directly supports the human innate-activation node and its resolution after clearance.
NS3/4A-mediated innate immune evasion
HCV NS3/4A protease cleaves and inactivates MAVS and TRIF, blunting pathogen-sensing pathways that induce interferons. Viral escape mutations can additionally reduce antibody and T-cell recognition.
Host-virus response balance determines clearance or persistence
hepatocyte CL:0000182 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hepatocyte (CL:0000182). CL:0000182 is a cell type from the Cell Ontology.
MAVS hgnc:29233 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves MAVS (hgnc:29233). hgnc:29233 is a gene from the HUGO Gene Nomenclature Committee.
symbiont-mediated suppression of host type I interferon-mediated signaling pathway GO:0039502 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased symbiont-mediated suppression of host type I interferon-mediated signaling pathway (GO:0039502). GO:0039502 is a biological process from the Gene Ontology. ↑ INCREASED type I interferon-mediated signaling pathway GO:0060337 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased type I interferon-mediated signaling pathway (GO:0060337). GO:0060337 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Persistent HCV viremia Suppressed interferon induction and escape from immune recognition are proposed contributors to failure of viral clearance, but their specific causal contribution to persistence is not isolated by the cited review. Host-virus response balance determines clearance or persistence
Show evidence (2 references)
PMID:25443342 SUPPORT In Vitro
"the HCV NS3/4A protease can efficiently cleave and inactivate two important signalling molecules in the sensory pathways that react to HCV pathogen-associated molecular patterns (PAMPs) to induce IFNs, i.e., the mitochondrial anti-viral signalling protein (MAVS) and the Toll-IL-1..."
This review directly supports the stated NS3/4A mechanism.
PMID:25443342 SUPPORT Other
"Escape from adaptive immune responses can be achieved by emergence of viral escape mutations that avoid recognition by antibodies and T cells."
This directly supports adaptive immune escape as an additional persistence mechanism.
HCV-specific adaptive immune response
Virus-specific T-cell responses emerge after the early innate response. Strong multispecific responses are associated with spontaneous clearance, whereas the recent liver-enriched Tfh1-like helper-cell refinement is based on chimpanzee data and remains unconfirmed in humans.
Host-virus response balance determines clearance or persistence Intrahepatic Tfh1-like CD4 response as a helper axis for HCV control
T cell CL:0000084 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves T cell (CL:0000084). CL:0000084 is a cell type from the Cell Ontology.
T cell activation GO:0042110 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased T cell activation (GO:0042110). GO:0042110 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Spontaneous viral clearance Early multispecific T-cell responses and low viral diversity are associated with untreated clearance, without establishing that the measured response is independently causal. Host-virus response balance determines clearance or persistence Intrahepatic Tfh1-like CD4 response as a helper axis for HCV control
Immune-associated hepatocellular injury Activated immune-cell populations track with biochemical hepatitis, but their causal contribution to hepatocyte killing remains unresolved. Host-virus response balance determines clearance or persistence Intrahepatic Tfh1-like CD4 response as a helper axis for HCV control
Persistent HCV viremia Adaptive responses can remain ongoing yet fail to clear immune-escape variants. Host-virus response balance determines clearance or persistence
Show evidence (2 references)
PMID:21139063 SUPPORT Human Clinical
"Evolution to spontaneous clearance occurred in patients with low viral diversity in the presence of an early multispecific T cell response."
This human cohort supports an association between early multispecific T-cell responses and clearance.
PMID:40956619 SUPPORT Model Organism
"circulating CD4+ T cells with high programmed cell death 1 (PD-1) and ICOS coexpression were temporally associated with onset of virus control, seroconversion, and hepatitis in HCV-infected chimpanzees."
This supports the emerging Tfh1-like refinement in the chimpanzee model, not direct human confirmation.
IFNL3 rs12979860 host-clearance modifier
The rs12979860 C/C genotype near IFNL3 (formerly IL28B) is associated with a higher probability of untreated HCV clearance in both European- and African-ancestry cohorts. The associated locus is established, but its precise functional mechanism remains unresolved.
Host-virus response balance determines clearance or persistence
IFNL3 hgnc:18365 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves IFNL3 (hgnc:18365). hgnc:18365 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Spontaneous viral clearance rs12979860 C/C is associated with spontaneous HCV clearance, while the molecular intermediates and causal mechanism remain unresolved. Host-virus response balance determines clearance or persistence
Show evidence (1 reference)
PMID:19759533 SUPPORT Human Clinical
"We show that the C/C genotype strongly enhances resolution of HCV infection among individuals of both European and African ancestry."
This multi-cohort human genetic study directly supports the rs12979860-clearance association.
Spontaneous viral clearance
Some acute infections lose detectable viremia without antiviral therapy. Clearance proportions vary by population and ascertainment; a small tertiary-center cohort observed clearance in 9 of 30 patients.
response to virus GO:0009615 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased response to virus (GO:0009615). GO:0009615 is a biological process from the Gene Ontology. ↑ INCREASED
Show evidence (1 reference)
PMID:23481134 SUPPORT Human Clinical
"Totally, 9 patients (30%) experienced spontaneous viral eradication."
This directly documents a spontaneous-clearance outcome in acute HCV.
Persistent HCV viremia
When host responses do not eradicate HCV, viremia persists despite ongoing innate and adaptive responses and can progress to chronic infection.
Host-virus response balance determines clearance or persistence
hepatocyte CL:0000182 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hepatocyte (CL:0000182). CL:0000182 is a cell type from the Cell Ontology.
viral genome replication GO:0019079 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased viral genome replication (GO:0019079). GO:0019079 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Chronic hepatitis C virus infection Viremia persisting beyond six months meets the definition of chronic HCV infection. Host-virus response balance determines clearance or persistence
Show evidence (1 reference)
PMID:25443342 SUPPORT Other
"However, the majority of patients is unable to clear the virus and develops viral persistence in face of an ongoing innate and adaptive immune response."
This directly supports the persistent-viremia state.
Chronic hepatitis C virus infection
Chronic HCV is the natural-history outcome in which viremia persists for more than six months after recent acquisition.
hepatocyte CL:0000182 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hepatocyte (CL:0000182). CL:0000182 is a cell type from the Cell Ontology.
viral process GO:0016032 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased viral process (GO:0016032). GO:0016032 is a biological process from the Gene Ontology. ↑ INCREASED
Show evidence (1 reference)
PMID:39599853 SUPPORT Human Clinical
"approximately 50-70% of individuals with recently acquired hepatitis C will develop a chronic infection, defined as the persistence of viremia for a period exceeding six months."
This directly supports the chronic outcome and its definition.
Immune-associated hepatocellular injury
Hepatocellular injury during acute HCV releases alanine aminotransferase and may produce symptomatic hepatitis. Human iNKT-cell activation correlates with ALT, but available data do not determine whether those cells cause injury or respond to the same inflammatory drivers.
Host-virus response balance determines clearance or persistence
hepatocyte CL:0000182 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hepatocyte (CL:0000182). CL:0000182 is a cell type from the Cell Ontology.
liver UBERON:0002107 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in liver (UBERON:0002107). UBERON:0002107 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Elevated hepatic transaminases Hepatocellular injury is reflected by increased circulating ALT and other hepatic transaminases. Host-virus response balance determines clearance or persistence
Jaundice Clinically apparent acute hepatitis can impair bilirubin handling and present with jaundice. Host-virus response balance determines clearance or persistence
Nausea Symptomatic acute hepatitis can include nausea through incompletely resolved systemic and gastrointestinal intermediates. Host-virus response balance determines clearance or persistence
Fatigue Symptomatic acute hepatitis can include fatigue through incompletely resolved systemic inflammatory intermediates. Host-virus response balance determines clearance or persistence
Anorexia Symptomatic acute hepatitis can include loss of appetite through incompletely resolved systemic and gastrointestinal intermediates. Host-virus response balance determines clearance or persistence
Show evidence (1 reference)
PMID:34905514 SUPPORT Human Clinical
"We next analyzed the activation status of iNKT cells in the context of liver damage, which is defined by serum levels of alanine transaminase (ALT)."
This human study operationalizes acute-HCV liver damage using ALT and supports the immune-associated injury node.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Acute Hepatitis C Virus Infection Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

5
Digestive 3
Jaundice HP:0000952 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Jaundice (HP:0000952). HP:0000952 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19124916 SUPPORT Human Clinical
"Out of 4 symptomatics 3 were with jaundice."
This small cohort directly documents jaundice in symptomatic acute/recent HCV without supporting a population frequency.
Nausea HP:0002018 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Nausea (HP:0002018). HP:0002018 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:29642211 SUPPORT Human Clinical
"a 26 year-old Chinese female acquired a tattoo and developed fatigue, nausea, and anorexia."
Case-level evidence supports possible presentation but not frequency.
Anorexia HP:0002039 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Anorexia (HP:0002039). HP:0002039 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:29642211 SUPPORT Human Clinical
"a 26 year-old Chinese female acquired a tattoo and developed fatigue, nausea, and anorexia."
Case-level evidence supports possible presentation but not frequency.
Metabolism 1
Elevated hepatic transaminases Elevated circulating hepatic transaminase concentration HP:0002910 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Elevated circulating hepatic transaminase concentration (HP:0002910). HP:0002910 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19124916 SUPPORT Human Clinical
"Among 12 asymptomatics: 8 had elevated ALT"
This cohort directly documents ALT elevation even among asymptomatic acute/recent infections.
Constitutional 1
Fatigue HP:0012378 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Fatigue (HP:0012378). HP:0012378 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:29642211 SUPPORT Human Clinical
"a 26 year-old Chinese female acquired a tattoo and developed fatigue, nausea, and anorexia."
Case-level evidence supports possible presentation but not frequency.
🧬

Genetic Associations

1
IFNL3 (IL28B) rs12979860 clearance modifier (The rs12979860 C/C genotype near IFNL3 is associated with an increased probability of spontaneous HCV clearance; it is not necessary or sufficient for clearance, and its precise functional mechanism remains unresolved.)
Gene: IFNL3 hgnc:18365 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is IFNL3 (hgnc:18365). hgnc:18365 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: MODIFIER variant_origin: GERMLINE
Show evidence (1 reference)
PMID:19759533 SUPPORT Human Clinical
"We show that the C/C genotype strongly enhances resolution of HCV infection among individuals of both European and African ancestry."
This multi-cohort human genetic study establishes rs12979860 as a modifier of spontaneous HCV clearance.
💊

Medical Actions

2
Immediate direct-acting antiviral treatment after confirmed acute HCV viremia
Action: antiviral therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is antiviral therapy (NCIT:C16119). NCIT:C16119 is a clinical intervention from the NCI Thesaurus. Ontology label: Antiviral Therapy NCIT:C16119
Published AASLD-IDSA guidance recommends initiating direct-acting antiviral treatment after acute HCV with quantifiable RNA is diagnosed rather than waiting for possible spontaneous resolution.
Show evidence (1 reference)
DOI:10.1002/hep.31060 SUPPORT Other
"After the initial diagnosis of acute HCV with viremia (defined as quantifiable RNA), HCV treatment should be initiated without awaiting spontaneous resolution."
The published AASLD-IDSA guidance directly supports the test-and-treat timing recommendation.
Eight-week glecaprevir/pibrentasvir therapy
Action: antiviral therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is antiviral therapy (NCIT:C16119). NCIT:C16119 is a clinical intervention from the NCI Thesaurus. Ontology label: Antiviral Therapy NCIT:C16119
Agent: glecaprevir NCIT:C170029 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses glecaprevir (NCIT:C170029). NCIT:C170029 is a therapeutic agent from the NCI Thesaurus. pibrentasvir NCIT:C166601 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses pibrentasvir (NCIT:C166601). NCIT:C166601 is a therapeutic agent from the NCI Thesaurus.
An eight-week oral glecaprevir/pibrentasvir direct-acting antiviral regimen produced high sustained virologic response rates in a completed single-arm phase IIIb study of adults with acute HCV. Glecaprevir is the regimen's NS3/4A protease inhibitor, whereas pibrentasvir inhibits NS5A. The absence of a randomized untreated comparator and geography-specific regulatory status should be considered when applying the result.
Mechanism Target:
INHIBITS HCV NS3/4A-Dependent Processing of the Nonstructural Polyprotein — The glecaprevir component directly inhibits HCV NS3/4A protease and therefore blocks NS3/4A-dependent nonstructural-polyprotein processing. Pibrentasvir acts through NS5A and is not represented by this protease-target edge.
Show evidence (2 references)
PMID:29084747 SUPPORT In Vitro
"Glecaprevir (formerly ABT-493) is a novel hepatitis C virus (HCV) NS3/4A protease inhibitor (PI) with pangenotypic activity."
The primary biochemical study directly identifies glecaprevir as an HCV NS3/4A protease inhibitor.
PMID:29084747 SUPPORT In Vitro
"It inhibited the enzymatic activity of purified NS3/4A proteases from HCV genotypes 1 to 6 in vitro"
The biochemical assay directly demonstrates glecaprevir inhibition of purified HCV NS3/4A proteases across genotypes.
INHIBITS HCV genome replication and early viremia — Direct-acting antiviral treatment suppresses acute HCV replication and enables virologic eradication.
Show evidence (1 reference)
PMID:41297677 SUPPORT Human Clinical
"An 8-week glecaprevir/pibrentasvir regimen was efficacious and well-tolerated in patients with acute HCV."
This directly supports regimen efficacy against acute infection; the molecular target detail is intentionally kept at the viral-replication level.
INHIBITS Persistent HCV viremia — Achieving sustained virologic response removes persistent viremia and prevents classification as chronic infection.
Show evidence (1 reference)
PMID:41297677 SUPPORT Human Clinical
"SVR12 was achieved by 96.2% (95% CI 93.2%-97.8%) in the ITT population (n = 286), and 100% in the mITT-VF population (n = 275)."
Sustained virologic response directly supports inhibition and eradication of persistent viremia in the study population.
Show evidence (2 references)
PMID:41297677 SUPPORT Human Clinical
"Overall, 286 adults were enrolled and treated; 14.3% were recent/current users of injection drugs, 49.7% were HCV/HIV coinfected, and 64.2% had HCV genotype 1."
This establishes the treated acute-HCV study population and its important clinical contexts.
PMID:41297677 SUPPORT Human Clinical
"SVR12 was achieved by 96.2% (95% CI 93.2%-97.8%) in the ITT population (n = 286), and 100% in the mITT-VF population (n = 275)."
This directly supports the high sustained virologic response achieved with the regimen.
🌍

Environmental Factors

1
Blood-exposure risk contexts
blood exposure ECTO:7000110 Environmental Conditions, Treatments and Exposures Ontology (ECTO) Relation: this environmental factor is this exposure This environmental factor is blood exposure, annotated with exposure to blood (ECTO:7000110). ECTO:7000110 is an exposure from the Environmental Conditions, Treatments and Exposures Ontology.
Injection drug use and unsafe medical procedures increase the opportunity for blood-borne HCV acquisition; HIV coinfection identifies an important clinical risk context but is not itself a transmission route.
Show evidence (1 reference)
PMID:36800699 SUPPORT Human Clinical
"People who have received unsafe medical procedures, used injection drugs, and lived with human immunodeficiency virus are reported to be most susceptible to acute HCV infection."
The source directly identifies these risk contexts while allowing HIV status to be distinguished from a route of transmission.
Mechanism Target:
TRIGGERS HCV attachment and hepatocyte entry — Hepatitis C is efficiently transmitted percutaneously, so unsafe injection and unsterile medical procedures put virus directly into blood, from which it reaches and attaches to hepatocytes.
Show evidence (1 reference)
PMID:36800699 SUPPORT Human Clinical
"People who have received unsafe medical procedures, used injection drugs, and lived with human immunodeficiency virus are reported to be most susceptible to acute HCV infection."
Identifies unsafe medical procedures and injection drug use among the contexts with the highest reported infection, the percutaneous blood-exposure routes this link describes.
🔬

Biochemical Markers

3
HCV RNA (Detected during active infection)
Context: Qualitative or quantitative HCV RNA establishes current infection but a single positive result does not by itself establish recent acquisition.
Pathograph Readouts
Readout Of HCV genome replication and early viremia Present Absent Diagnostic
Detectable circulating HCV RNA reports active viremia.
Show evidence (1 reference)
PMID:23481134 SUPPORT Human Clinical
"HCV-ribonucleic acid (RNA) was detectable at presentation in 26 (86.7%) patients."
This directly supports HCV RNA as a viremia readout in acute infection.
Show evidence (1 reference)
PMID:30927209 SUPPORT Human Clinical
"Tests for HCV RNA are valuable in distinguishing between active and resolved infection, but the presence of HCV RNA does not distinguish between acute and chronic hepatitis C"
This directly supports the use and limitation of HCV RNA as a biomarker.
Anti-HCV antibody (Negative before seroconversion or positive after seroconversion)
Context: Anti-HCV may be absent early and, once present, cannot distinguish active, resolved, acute, or chronic infection without RNA results and longitudinal context.
Show evidence (1 reference)
PMID:30927209 SUPPORT Human Clinical
"Anti-HCV antibodies are usually used to exclude acute hepatitis C in a patient with acute liver injury, but it does not distinguish between acute, chronic or resolved hepatitis."
This directly supports the interpretive limitation of anti-HCV antibody.
Alanine aminotransferase (Increased or fluctuating during acute hepatocellular injury)
Context: Serum ALT reports hepatocellular injury. It is not specific for HCV and can be elevated in clinically silent infection.
Pathograph Readouts
Readout Of Immune-associated hepatocellular injury Positive Diagnostic
ALT is a biochemical readout of liver injury, not proof of a particular immune effector mechanism.
Show evidence (1 reference)
PMID:34905514 SUPPORT Human Clinical
"We next analyzed the activation status of iNKT cells in the context of liver damage, which is defined by serum levels of alanine transaminase (ALT)."
This directly identifies ALT as the study's liver-damage readout.
Show evidence (1 reference)
PMID:19124916 SUPPORT Human Clinical
"Among 12 asymptomatics: 8 had elevated ALT"
This directly documents ALT elevation in asymptomatic acute/recent infection.
🔬

Diagnosis

3
Combined HCV RNA and anti-HCV testing with evidence of recent acquisition
Acute infection is best supported by HCV RNA during the antibody-negative window, documented anti-HCV seroconversion, de novo RNA detection, or RNA loss during untreated recovery. RNA or antibody at one time point cannot by itself reliably distinguish acute from chronic infection.
diagnostic procedure NCIT:C18020 NCI Thesaurus (NCIT)
Results: Current HCV RNA plus a documented recent negative result, seroconversion, or compatible longitudinal course supports acute HCV.
Show evidence (1 reference)
PMID:30927209 SUPPORT Human Clinical
"Thus, reliable diagnosis of acute hepatitis C usually requires testing at two time points demonstrating seroconversion to anti-HCV reactivity, de novo development of HCV RNA, or loss of HCV RNA during recovery."
This directly supports longitudinal antibody/RNA evidence for recent infection.
Serial HCV RNA assessment
Repeat HCV RNA assessment is important when timing is uncertain because untreated viremia may fluctuate and a transient decline does not establish spontaneous clearance.
diagnostic procedure NCIT:C18020 NCI Thesaurus (NCIT)
Results: Persistent, recurrent, or cleared RNA across serial measurements resolves uncertainty that remains after a single result.
Show evidence (1 reference)
PMID:21139063 SUPPORT Human Clinical
"The latter group included a significant proportion of 'fluctuating' progressors (37.5%), in whom a fall followed by a rise (>1 log₁₀) in viraemia was observed."
This directly supports serial rather than single-point interpretation of viremia, with the cohort context stated in progression.
Combined HCV antibody and antigen immunoassay
A fourth-generation antibody/antigen assay can shorten the diagnostic window but does not eliminate the need for nucleic-acid testing.
serology testing NCIT:C25294 NCI Thesaurus (NCIT)
Results: Antibody/antigen reactivity is an early-detection adjunct and should be interpreted with HCV RNA testing.
Show evidence (1 reference)
PMID:39283072 SUPPORT Human Clinical
"Fourth generation HCV Duo Ab/Ag assay demonstrated comparable performance to SOC testing and shortens the diagnostic window but does not eliminate the need for NAAT in all patients."
This diagnostic study directly supports the stated adjunctive role and limitation.
📈

Progression

5
Recent acquisition and early viremia
Duration: Up to six months before persistent infection is classified as chronic
Acute infection begins with recent HCV acquisition and detectable viremia. The six-month boundary is a clinical definition of chronicity rather than a claim that every untreated infection remains biologically unchanged until that time.
Show evidence (1 reference)
PMID:39599853 SUPPORT Human Clinical
"approximately 50-70% of individuals with recently acquired hepatitis C will develop a chronic infection, defined as the persistence of viremia for a period exceeding six months."
This defines the recent-infection phase and the six-month chronicity boundary.
Clinically silent or symptomatic acute presentation
Many infections are not diagnosed during the acute phase because the course is predominantly asymptomatic. A minority present with clinically apparent hepatitis.
Show evidence (1 reference)
PMID:23481134 SUPPORT Human Clinical
"Acute hepatitis C is rarely diagnosed due to its predominantly asymptomatic course."
This directly supports clinically silent presentation as a major feature of the acute phase.
Spontaneous viral clearance
Clearance can occur without antiviral treatment. The observed proportion varies by cohort; one tertiary-center series reported clearance in 9 of 30 patients and should not be treated as a universal population frequency.
Show evidence (1 reference)
PMID:23481134 SUPPORT Human Clinical
"Totally, 9 patients (30%) experienced spontaneous viral eradication."
This cohort directly documents untreated spontaneous clearance while the note limits generalization of its frequency.
Fluctuating viremia during unresolved infection
Serial viral loads can fall and then rise. The quantified 37.5% fluctuation estimate came from an HIV-1-positive male cohort and is retained only as evidence that a single decline does not establish clearance.
Show evidence (1 reference)
PMID:21139063 SUPPORT Human Clinical
"The latter group included a significant proportion of 'fluctuating' progressors (37.5%), in whom a fall followed by a rise (>1 log₁₀) in viraemia was observed."
This cohort directly demonstrates fluctuating viremia among patients who progressed.
Chronic HCV infection
Duration: More than six months of persistent viremia
Failure to clear HCV leads to persistent viremia and classification as chronic hepatitis C.
Show evidence (1 reference)
PMID:39599853 SUPPORT Human Clinical
"approximately 50-70% of individuals with recently acquired hepatitis C will develop a chronic infection, defined as the persistence of viremia for a period exceeding six months."
This directly supports both the outcome frequency range and definition of chronicity.
📊

Prevalence

2
Global (all ages)
Annual Incidence Unknown
The Global Burden of Disease 2019 analysis estimated 6.2 million new HCV infections worldwide in 2019. This is an incidence estimate for newly acquired infection, not the prevalence of symptomatic acute hepatitis.
Show evidence (1 reference)
PMID:36935711 SUPPORT Human Clinical
"It was estimated that 6.2 million new HCV infections, 0.54 million HCV-related deaths, and 15.3 million DALYs worldwide in 2019, with an increase of 25.4, 59.1, and 43.6%, respectively, from 1990"
This GBD analysis quantifies global incident HCV infection in 2019.
Global women of reproductive age (15-49 years)
Annual Incidence Unknown
In a GBD analysis restricted to reproductive-age women, global acute-HCV incidence increased by 46.45% from 1990 through 2019; this is a trend rather than an individual-level risk estimate.
Show evidence (1 reference)
PMID:38638097 SUPPORT Human Clinical
"Over the 30 years, global incidences of AHC and HCV-related cirrhosis in reproductive-age women increased by 46.45 and 72.74%, respectively."
This directly supports the acute-HCV incidence trend in the specified population.
🦠

Infectious Agent

1
Hepatitis C virus
Hepacivirus hominis is the enveloped RNA virus whose productive entry into human liver cells initiates acute hepatitis C.
Hepacivirus hominis NCBITaxon:3052230 NCBI Taxonomy (NCBITaxon)
Show evidence (1 reference)
PMID:31427285 SUPPORT Other
"Numerous host factors including proteins, lipids, and glycans promote productive uptake of HCV particles into human liver cells."
This review directly identifies HCV particles as the agent productively entering human liver cells.
↔️

Transmission

1
Parenteral and blood-borne acquisition
Acute HCV is acquired through blood exposure. Important observed contexts include injection drug use and unsafe medical procedures.
Show evidence (2 references)
PMID:36800699 SUPPORT Human Clinical
"People who have received unsafe medical procedures, used injection drugs, and lived with human immunodeficiency virus are reported to be most susceptible to acute HCV infection."
This review identifies major human exposure contexts for acute HCV acquisition.
PMID:23481134 SUPPORT Human Clinical
"The source of infection was mainly injection drug use in 17/30 (56.7) and medical procedures 6/30 (20%)."
This acute-HCV cohort documents injection drug use and medical procedures as observed acquisition sources.
🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from Acute Hepatitis C Virus Infection:

Drug-induced liver injury Not Yet Curated MONDO:0005359
Overlapping Features Drug-induced liver injury can closely mimic the hepatocellular presentation of acute HCV. Medication and supplement exposure, dechallenge, and formal causality assessment are interpreted alongside both anti-HCV and HCV RNA.
Distinguishing Features
  • A compatible drug or supplement exposure and improvement after withdrawal favor drug-induced injury.
  • HCV RNA during an antibody-negative window or longitudinal seroconversion favors acute HCV.
Show evidence (1 reference)
PMID:30927209 SUPPORT Human Clinical
"These findings indicate that patients presenting with acute hepatocellular injury, even with features suggestive of DILI, should be tested for both anti-HCV and HCV RNA to reliably exclude acute HCV infection."
This prospective DILI-network analysis directly supports distinguishing acute HCV from DILI using both tests.
Other viral, autoimmune, and biliary causes of acute hepatocellular injury
Overlapping Features Hepatitis A, B, and E, autoimmune hepatitis, and biliary disease can produce an overlapping acute-hepatitis presentation and require cause-specific testing when HCV timing is uncertain.
Distinguishing Features
  • Cause-specific viral testing distinguishes hepatitis A, B, or E.
  • Autoimmune evaluation and biliary imaging are guided by the presentation.
  • Longitudinal anti-HCV and HCV RNA results establish or weaken recent-HCV timing.
Show evidence (1 reference)
PMID:30927209 SUPPORT Human Clinical
"These assessments could include testing for hepatitis A, B, C, E, infectious mononucleosis, iron overload, and autoimmune conditions, as well as imaging for biliary tract disease10."
This human diagnostic cohort directly supports the listed alternative-cause workup.
📊

Related Datasets

3
Longitudinal transcriptomic characterization of the immune response to acute hepatitis C virus infection geo:GSE119117
Most individuals exposed to hepatitis C virus (HCV) become persistently infected while a minority spontaneously eliminate the virus. Although early immune events influence infection outcome, the cellular composition, molecular effectors, and timeframe of the host response active shortly after viral exposure remain incompletely understood. Employing specimens collected from people who inject drugs (PWID) with high risk of HCV exposure, we utilized RNA-Seq to characterize immune function in peripheral blood before, during, and after acute HCV infection resulting in spontaneous resolution.
human BULK RNA SEQ n=53
PMID:30222771
Identified by GEO DataSets index search for Acute Hepatitis C Virus Infection (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
Hepatitis C Virus-induced Differential Transcriptional Traits in Host Cells After Persistent Infection Elimination by Direct-Acting Antivirals In Cell Culture geo:GSE267834
Chronic hepatitis C virus infection (HCV) causes liver inflammation and fibrosis, leading to development of severe liver disease, such as cirrhosis or hepatocellular carcinoma (HCC). Approval of direct acting antiviral (DAA) drug combinations has revolutionized chronic HCV therapy, with virus eradication in >98% of the treated patients. The efficacy of these treatments is such that it is formally possible for cured patients to carry formerly infected cells that display irreversible transcriptional alterations directly caused by chronic HCV Infection.
human BULK RNA SEQ n=28
PMID:38988177
Identified by GEO DataSets index search for Acute Hepatitis C Virus Infection (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
Gene expression analysis during acute hepatitis C virus infection associates dendritic cell activation with viral clearance geo:GSE65123
Background and Aims: Viral clearance during acute hepatitis C virus (HCV) infection is associated with the induction of potent antiviral T-cell responses. Since dendritic cells (DC) are essential in the activation of primary T-cell responses our goal was to analyze gene expression in DC from patients during acute HCV infection. Methods: By using microarrays, gene expression was compared in resting and activated peripheral blood plasmacytoid (pDC) and myeloid (mDC) DC from acute HCV resolving patients (AR) and from those who become chronically infected (ANR), as well as in HCV chronically infected patients (CHR) and healthy seronegative individuals (CTRL).
human MICROARRAY n=56
PMID:26447929
Identified by GEO DataSets index search for Acute Hepatitis C Virus Infection (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
🔬

Clinical Trials

1
NCT04903626 PHASE_III COMPLETED
Completed multicenter, single-arm phase IIIb study of eight weeks of oral glecaprevir/pibrentasvir in adults with acute HCV. The publication reports 286 treated adults and 96.2% ITT SVR12 (95% CI 93.2%-97.8%).
Show evidence (2 references)
clinicaltrials:NCT04903626 SUPPORT Human Clinical
"Participants will receive oral tablets of GLE/PIB once daily (QD) for 8 weeks and will be followed for 12 weeks after the end of treatment."
The registry directly establishes the regimen and follow-up schedule.
PMID:41297677 SUPPORT Human Clinical
"SVR12 was achieved by 96.2% (95% CI 93.2%-97.8%) in the ITT population (n = 286), and 100% in the mITT-VF population (n = 275)."
The peer-reviewed phase IIIb report supplies the completed efficacy result.
{ }

Source YAML

click to show 
name: Acute Hepatitis C Virus Infection
creation_date: '2026-05-04T19:32:38Z'
description: >-
  Acute hepatitis C virus infection is the early phase after acquisition of
  hepatitis C virus (HCV), before either spontaneous viral clearance or
  persistent infection is established. The course is often clinically silent;
  symptomatic hepatitis can include jaundice, nausea, fatigue, anorexia, and
  elevated hepatic transaminases. Diagnosis requires both evidence of current
  infection and evidence that acquisition was recent because anti-HCV and HCV
  RNA results considered at a single time point do not reliably separate acute
  from chronic infection. Early direct-acting antiviral therapy can eradicate
  viremia and prevent chronic infection.
category: Infectious Disease
synonyms:
- Acute HCV infection
- Recently acquired hepatitis C virus infection
disease_term:
  preferred_term: acute hepatitis C virus infection
  term:
    id: MONDO:0100371
    label: acute hepatitis C virus infection
parents:
- Acute disease
- Hepatitis C virus infection
classifications:
  harrisons_chapter:
  - classification_value: INFECTIOUS_DISEASES
    evidence:
    - reference: PMID:39599853
      reference_title: "Acute Hepatitis C: Current Status and Future Perspectives."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The hepatitis C virus (HCV) infection continues to represent a
        significant public health threat and is a leading cause of liver
        cirrhosis, liver cancer, and liver-related mortality.
      explanation: HCV is the infectious cause of acute hepatitis C.
  - classification_value: GASTROINTESTINAL
    evidence:
    - reference: PMID:31427285
      reference_title: "Hepatitis C Virus Entry: Protein Interactions and Fusion Determinants Governing Productive Hepatocyte Invasion."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Numerous host factors including proteins, lipids, and glycans promote
        productive uptake of HCV particles into human liver cells.
      explanation: HCV productively invades liver cells, placing the disease in the liver and gastrointestinal chapter.
infectious_agent:
- name: Hepatitis C virus
  infectious_agent_term:
    preferred_term: Hepacivirus hominis
    term:
      id: NCBITaxon:3052230
      label: Hepacivirus hominis
  description: >-
    Hepacivirus hominis is the enveloped RNA virus whose productive entry into
    human liver cells initiates acute hepatitis C.
  evidence:
  - reference: PMID:31427285
    reference_title: "Hepatitis C Virus Entry: Protein Interactions and Fusion Determinants Governing Productive Hepatocyte Invasion."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Numerous host factors including proteins, lipids, and glycans promote
      productive uptake of HCV particles into human liver cells.
    explanation: This review directly identifies HCV particles as the agent productively entering human liver cells.
transmission:
- name: Parenteral and blood-borne acquisition
  description: >-
    Acute HCV is acquired through blood exposure. Important observed contexts
    include injection drug use and unsafe medical procedures.
  evidence:
  - reference: PMID:36800699
    reference_title: "Acute hepatitis C virus infection: clinical update and remaining challenges."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      People who have received unsafe medical procedures, used injection drugs,
      and lived with human immunodeficiency virus are reported to be most
      susceptible to acute HCV infection.
    explanation: This review identifies major human exposure contexts for acute HCV acquisition.
  - reference: PMID:23481134
    reference_title: "Clinical characteristics, spontaneous clearance and treatment outcome of acute hepatitis C: a single tertiary center experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The source of infection was mainly injection drug use in 17/30 (56.7) and
      medical procedures 6/30 (20%).
    explanation: This acute-HCV cohort documents injection drug use and medical procedures as observed acquisition sources.
environmental:
- name: Blood-exposure risk contexts
  exposure_term:
    preferred_term: blood exposure
    term:
      id: ECTO:7000110
      label: exposure to blood
  influences_mechanisms:
  - target: HCV attachment and hepatocyte entry
    environmental_effect: TRIGGERS
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Hepatitis C is efficiently transmitted percutaneously, so unsafe
      injection and unsterile medical procedures put virus directly into
      blood, from which it reaches and attaches to hepatocytes.
    evidence:
    - reference: PMID:36800699
      reference_title: "Acute hepatitis C virus infection: clinical update and remaining challenges."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "People who have received unsafe medical procedures, used injection drugs, and lived with human immunodeficiency virus are reported to be most susceptible to acute HCV infection."
      explanation: >-
        Identifies unsafe medical procedures and injection drug use among the
        contexts with the highest reported infection, the percutaneous
        blood-exposure routes this link describes.
  description: >-
    Injection drug use and unsafe medical procedures increase the opportunity
    for blood-borne HCV acquisition; HIV coinfection identifies an important
    clinical risk context but is not itself a transmission route.
  evidence:
  - reference: PMID:36800699
    reference_title: "Acute hepatitis C virus infection: clinical update and remaining challenges."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      People who have received unsafe medical procedures, used injection drugs,
      and lived with human immunodeficiency virus are reported to be most
      susceptible to acute HCV infection.
    explanation: The source directly identifies these risk contexts while allowing HIV status to be distinguished from a route of transmission.
prevalence:
- population: Global (all ages)
  measure_type: ANNUAL_INCIDENCE
  prevalence_class: UNKNOWN
  notes: >-
    The Global Burden of Disease 2019 analysis estimated 6.2 million new HCV
    infections worldwide in 2019. This is an incidence estimate for newly
    acquired infection, not the prevalence of symptomatic acute hepatitis.
  evidence:
  - reference: PMID:36935711
    reference_title: "The burden of hepatitis C virus in the world, China, India, and the United States from 1990 to 2019."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It was estimated that 6.2 million new HCV infections, 0.54 million
      HCV-related deaths, and 15.3 million DALYs worldwide in 2019, with an
      increase of 25.4, 59.1, and 43.6%, respectively, from 1990
    explanation: This GBD analysis quantifies global incident HCV infection in 2019.
- population: Global women of reproductive age (15-49 years)
  measure_type: ANNUAL_INCIDENCE
  prevalence_class: UNKNOWN
  notes: >-
    In a GBD analysis restricted to reproductive-age women, global acute-HCV
    incidence increased by 46.45% from 1990 through 2019; this is a trend rather
    than an individual-level risk estimate.
  evidence:
  - reference: PMID:38638097
    reference_title: "Epidemiology of acute hepatitis C and hepatitis C virus-related cirrhosis in reproductive-age women, 1990-2019: An analysis of the Global Burden of Disease study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Over the 30 years, global incidences of AHC and HCV-related cirrhosis in
      reproductive-age women increased by 46.45 and 72.74%, respectively.
    explanation: This directly supports the acute-HCV incidence trend in the specified population.
progression:
- phase: Recent acquisition and early viremia
  duration: Up to six months before persistent infection is classified as chronic
  notes: >-
    Acute infection begins with recent HCV acquisition and detectable viremia.
    The six-month boundary is a clinical definition of chronicity rather than a
    claim that every untreated infection remains biologically unchanged until
    that time.
  evidence:
  - reference: PMID:39599853
    reference_title: "Acute Hepatitis C: Current Status and Future Perspectives."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      approximately 50-70% of individuals with recently acquired hepatitis C
      will develop a chronic infection, defined as the persistence of viremia
      for a period exceeding six months.
    explanation: This defines the recent-infection phase and the six-month chronicity boundary.
- phase: Clinically silent or symptomatic acute presentation
  notes: >-
    Many infections are not diagnosed during the acute phase because the course
    is predominantly asymptomatic. A minority present with clinically apparent
    hepatitis.
  evidence:
  - reference: PMID:23481134
    reference_title: "Clinical characteristics, spontaneous clearance and treatment outcome of acute hepatitis C: a single tertiary center experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Acute hepatitis C is rarely diagnosed due to its predominantly asymptomatic course.
    explanation: This directly supports clinically silent presentation as a major feature of the acute phase.
- phase: Spontaneous viral clearance
  notes: >-
    Clearance can occur without antiviral treatment. The observed proportion
    varies by cohort; one tertiary-center series reported clearance in 9 of 30
    patients and should not be treated as a universal population frequency.
  evidence:
  - reference: PMID:23481134
    reference_title: "Clinical characteristics, spontaneous clearance and treatment outcome of acute hepatitis C: a single tertiary center experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Totally, 9 patients (30%) experienced spontaneous viral eradication.
    explanation: This cohort directly documents untreated spontaneous clearance while the note limits generalization of its frequency.
- phase: Fluctuating viremia during unresolved infection
  notes: >-
    Serial viral loads can fall and then rise. The quantified 37.5% fluctuation
    estimate came from an HIV-1-positive male cohort and is retained only as
    evidence that a single decline does not establish clearance.
  evidence:
  - reference: PMID:21139063
    reference_title: Predicting spontaneous clearance of acute hepatitis C virus in a large cohort of HIV-1-infected men.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The latter group included a significant proportion of 'fluctuating'
      progressors (37.5%), in whom a fall followed by a rise (>1 log₁₀) in
      viraemia was observed.
    explanation: This cohort directly demonstrates fluctuating viremia among patients who progressed.
- phase: Chronic HCV infection
  duration: More than six months of persistent viremia
  notes: >-
    Failure to clear HCV leads to persistent viremia and classification as
    chronic hepatitis C.
  evidence:
  - reference: PMID:39599853
    reference_title: "Acute Hepatitis C: Current Status and Future Perspectives."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      approximately 50-70% of individuals with recently acquired hepatitis C
      will develop a chronic infection, defined as the persistence of viremia
      for a period exceeding six months.
    explanation: This directly supports both the outcome frequency range and definition of chronicity.
mechanistic_hypotheses:
- hypothesis_group_id: canonical_acute_hcv_clearance_persistence_model
  hypothesis_label: Host-virus response balance determines clearance or persistence
  status: CANONICAL
  description: >-
    Productive hepatocyte infection generates viremia and innate antiviral
    activation while HCV simultaneously suppresses interferon induction.
    Adaptive immune responses can accompany clearance, but ongoing immune
    responses and viral escape can coexist with persistence. Hepatocellular
    injury is immune-associated, although the contribution of individual cell
    populations is not fully resolved.
  evidence:
  - reference: PMID:25443342
    reference_title: Innate and adaptive immune responses in HCV infections.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Elimination of HCV during acute infection correlates with a rapid
      induction of innate, especially interferon (IFN) induced genes, and a
      delayed induction of adaptive immune responses.
    explanation: This review supports the canonical coordination of innate and adaptive responses in acute-HCV outcome.
- hypothesis_group_id: intrahepatic_tfh1_helper_refinement
  hypothesis_label: Intrahepatic Tfh1-like CD4 response as a helper axis for HCV control
  status: EMERGING
  description: >-
    A recent chimpanzee study proposes that liver-enriched HCV-specific
    PD-1-high ICOS-high Tfh1-like CD4 cells help B-cell and CD8-cell responses
    at the site of replication. This refines the general adaptive-response node
    but is not asserted as a confirmed human mechanism.
  evidence:
  - reference: PMID:40956619
    reference_title: "A liver-infiltrating CD4+ Tfh1 cell response predicts HCV control, hepatitis, and seroconversion during acute infection."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      HCV-specific PD-1hiICOShi CD4+ Tfh1-like cells were enriched in liver,
      suggesting the potential for B and CD8+ T cell help at the site of virus
      replication.
    explanation: The chimpanzee study directly supports the proposed helper-cell refinement while not establishing it in humans.
pathophysiology:
- name: HCV attachment and hepatocyte entry
  description: >-
    HCV first attaches to cell-surface proteoglycans, SR-BI, and CD81, then uses
    the tight-junction proteins claudin-1 and occludin and clathrin-mediated
    endocytosis to enter human liver cells.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  locations:
  - preferred_term: liver
    term:
      id: UBERON:0002107
      label: liver
  biological_processes:
  - preferred_term: symbiont entry into host cell
    modifier: INCREASED
    term:
      id: GO:0046718
      label: symbiont entry into host cell
  evidence:
  - reference: PMID:31427285
    reference_title: "Hepatitis C Virus Entry: Protein Interactions and Fusion Determinants Governing Productive Hepatocyte Invasion."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The virus initially attaches to surface proteoglycans, lipid receptors
      such as the scavenger receptor BI (SR-BI), and to the tetraspanin CD81.
      After lateral translocation of virions to tight junctions, claudin-1
      (CLDN1) and occludin (OCLN) are essential for entry.
    explanation: This review directly supports the host-factor sequence in the entry node.
  downstream:
  - target: HCV Polyprotein Translation
    description: >-
      Productive hepatocyte entry and genome release permit translation of the
      HCV polyprotein.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Endosomal fusion and release of the positive-sense viral RNA genome
    evidence:
    - reference: PMID:31427285
      reference_title: "Hepatitis C Virus Entry: Protein Interactions and Fusion Determinants Governing Productive Hepatocyte Invasion."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Numerous host factors including proteins, lipids, and glycans promote
        productive uptake of HCV particles into human liver cells.
      explanation: >-
        Productive uptake supports the entry side of the edge; polyprotein
        translation after genome release is independently evidenced at the
        target node.
- name: HCV Polyprotein Translation
  biological_scale: MOLECULAR
  conforms_to: "viral_protease_inhibition#Synthesis of the Viral Polyprotein Precursor"
  role: trigger
  description: >-
    The positive-sense HCV RNA genome is translated as a single long
    polyprotein in infected hepatocytes. Host and viral proteases subsequently
    process this precursor into structural and nonstructural proteins.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  locations:
  - preferred_term: liver
    term:
      id: UBERON:0002107
      label: liver
  biological_processes:
  - preferred_term: Viral Gene Expression
    term:
      id: GO:0019080
      label: viral gene expression
    modifier: INCREASED
  evidence:
  - reference: PMID:22558217
    reference_title: "New details of HCV NS3/4A proteinase functionality revealed by a high-throughput cleavage assay."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The hepatitis C virus (HCV) genome encodes a long polyprotein, which is
      processed by host cell and viral proteases to the individual structural
      and non-structural (NS) proteins.
    explanation: >-
      The primary cleavage-assay study establishes the HCV polyprotein
      precursor and its processing into individual viral proteins.
  downstream:
  - target: HCV NS3/4A-Dependent Processing of the Nonstructural Polyprotein
    description: >-
      The viral NS3/4A serine protease cleaves defined sites in the
      nonstructural region of the HCV polyprotein.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: DIRECT
- name: HCV NS3/4A-Dependent Processing of the Nonstructural Polyprotein
  biological_scale: MOLECULAR
  conforms_to: "viral_protease_inhibition#Virus-Encoded Protease-Dependent Polyprotein Processing"
  role: therapeutic_vulnerability
  description: >-
    HCV NS3/4A is a virus-encoded serine protease complex that cleaves four
    defined junctions in the nonstructural region of the HCV polyprotein. This
    processing is essential for viral replication and produces active viral
    proteins, including NS3/4A itself. The active protease can also cleave host
    innate-sensing adaptors, a distinct downstream immune-evasion effect.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  locations:
  - preferred_term: liver
    term:
      id: UBERON:0002107
      label: liver
  biological_processes:
  - preferred_term: Viral Protein Processing
    term:
      id: GO:0019082
      label: viral protein processing
    modifier: INCREASED
  molecular_functions:
  - preferred_term: Peptidase Activity
    term:
      id: GO:0008233
      label: peptidase activity
  evidence:
  - reference: PMID:22558217
    reference_title: "New details of HCV NS3/4A proteinase functionality revealed by a high-throughput cleavage assay."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      NS3/4A cleaves the polyprotein sequence at four specific regions.
    explanation: >-
      The primary cleavage-assay study directly establishes four specific
      NS3/4A-dependent polyprotein cleavage regions.
  - reference: PMID:22558217
    reference_title: "New details of HCV NS3/4A proteinase functionality revealed by a high-throughput cleavage assay."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      NS3/4A is essential for viral replication and has been considered an
      attractive drug target.
    explanation: >-
      The study directly links NS3/4A activity to viral replication and its
      therapeutic vulnerability.
  downstream:
  - target: HCV genome replication and early viremia
    description: >-
      NS3/4A-dependent processing releases nonstructural proteins required for
      HCV genome replication.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Release of processed HCV nonstructural proteins
    - Assembly of the HCV replication complex
    evidence:
    - reference: PMID:22558217
      reference_title: "New details of HCV NS3/4A proteinase functionality revealed by a high-throughput cleavage assay."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        NS3/4A is essential for viral replication and has been considered an
        attractive drug target.
      explanation: >-
        The primary cleavage study directly links NS3/4A processing activity
        to the viral-replication output represented by this edge.
  - target: NS3/4A-mediated innate immune evasion
    description: >-
      Processed active NS3/4A also cleaves the host innate-sensing adaptors MAVS
      and TRIF, suppressing interferon induction.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Release and assembly of the active NS3/4A protease complex
    evidence:
    - reference: PMID:25443342
      reference_title: Innate and adaptive immune responses in HCV infections.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        the HCV NS3/4A protease can efficiently cleave and inactivate two
        important signalling molecules in the sensory pathways that react to
        HCV pathogen-associated molecular patterns (PAMPs) to induce IFNs,
        i.e., the mitochondrial anti-viral signalling protein (MAVS) and the
        Toll-IL-1 receptor-domain-containing adaptor-inducing IFN-β (TRIF).
      explanation: >-
        The review directly supports cleavage of MAVS and TRIF by active
        NS3/4A; release of that protease from the polyprotein is the stated
        intermediate.
- name: HCV genome replication and early viremia
  biological_scale: CELLULAR
  conforms_to: "viral_protease_inhibition#Replication-Complex Formation and Viral RNA Replication"
  role: effector
  description: >-
    Processed HCV nonstructural proteins assemble the replication complex that
    synthesizes viral RNA in infected hepatocytes, producing the circulating
    HCV RNA that marks productive acute infection. In one tertiary-center
    cohort, RNA was detectable at presentation in 26 of 30 patients; this cohort
    proportion is not assigned as a universal frequency.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  locations:
  - preferred_term: liver
    term:
      id: UBERON:0002107
      label: liver
  biological_processes:
  - preferred_term: Viral RNA Genome Replication
    modifier: INCREASED
    term:
      id: GO:0039694
      label: viral RNA genome replication
  evidence:
  - reference: PMID:23481134
    reference_title: "Clinical characteristics, spontaneous clearance and treatment outcome of acute hepatitis C: a single tertiary center experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: HCV-ribonucleic acid (RNA) was detectable at presentation in 26 (86.7%) patients.
    explanation: This acute-HCV cohort directly documents early detectable viremia.
  downstream:
  - target: Interferon-driven innate and NK-cell activation
    description: Acute HCV infection is accompanied by a transient type-I-interferon-imprinted activated NK-cell population.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Viral RNA sensing and type I interferon induction
    evidence:
    - reference: PMID:41453396
      reference_title: Transient Interferon-Driven Natural Killer Cell Activation in Acute Hepatitis C.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        At the transcriptomic level, we identified a subset of highly activated
        NK cells with a robust type I interferon imprint.
      explanation: Longitudinal human data directly support interferon-imprinted NK-cell activation during acute HCV.
  - target: Immune-associated hepatocellular injury
    description: >-
      Acute HCV viremia is associated with inflammatory immune activation and
      hepatocellular injury, but the exact direction and cell-specific causal
      contribution remain unresolved.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: UNKNOWN
    evidence:
    - reference: PMID:34905514
      reference_title: Peripheral blood iNKT cell activation correlates with liver damage during acute hepatitis C.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Given the correlative nature of our study, we cannot distinguish whether
        iNKT cell activation contributes to hepatocyte killing or whether ALT
        elevation
      explanation: Human data support immune activation accompanying injury while explicitly requiring UNKNOWN causal directness.
- name: Interferon-driven innate and NK-cell activation
  description: >-
    During acute HCV, a highly activated NK-cell subset shows a strong type I
    interferon imprint and largely returns toward baseline after viral
    clearance.
  cell_types:
  - preferred_term: natural killer cell
    term:
      id: CL:0000623
      label: natural killer cell
  biological_processes:
  - preferred_term: natural killer cell activation
    modifier: INCREASED
    term:
      id: GO:0030101
      label: natural killer cell activation
  - preferred_term: type I interferon-mediated signaling pathway
    modifier: INCREASED
    term:
      id: GO:0060337
      label: type I interferon-mediated signaling pathway
  evidence:
  - reference: PMID:41453396
    reference_title: Transient Interferon-Driven Natural Killer Cell Activation in Acute Hepatitis C.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Collectively, these data suggest an interferon-driven rise of an activated
      NK cell population during acute hepatitis C that is largely restored upon
      viral clearance.
    explanation: This directly supports the human innate-activation node and its resolution after clearance.
  downstream:
  - target: HCV-specific adaptive immune response
    description: >-
      Early interferon-associated innate activation precedes the later adaptive
      response associated with control or persistence, but the cited temporal
      pattern does not establish that NK-cell activation causes the adaptive
      response.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: UNKNOWN
    evidence:
    - reference: PMID:25443342
      reference_title: Innate and adaptive immune responses in HCV infections.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Elimination of HCV during acute infection correlates with a rapid
        induction of innate, especially interferon (IFN) induced genes, and a
        delayed induction of adaptive immune responses.
      explanation: The review supports temporal ordering of the responses but does not establish a causal NK-cell-to-adaptive-response link.
- name: NS3/4A-mediated innate immune evasion
  description: >-
    HCV NS3/4A protease cleaves and inactivates MAVS and TRIF, blunting
    pathogen-sensing pathways that induce interferons. Viral escape mutations
    can additionally reduce antibody and T-cell recognition.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  genes:
  - preferred_term: MAVS
    term:
      id: hgnc:29233
      label: MAVS
  biological_processes:
  - preferred_term: symbiont-mediated suppression of host type I interferon-mediated signaling pathway
    modifier: INCREASED
    term:
      id: GO:0039502
      label: symbiont-mediated suppression of host type I interferon-mediated signaling pathway
  - preferred_term: type I interferon-mediated signaling pathway
    modifier: DECREASED
    term:
      id: GO:0060337
      label: type I interferon-mediated signaling pathway
  evidence:
  - reference: PMID:25443342
    reference_title: Innate and adaptive immune responses in HCV infections.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      the HCV NS3/4A protease can efficiently cleave and inactivate two
      important signalling molecules in the sensory pathways that react to HCV
      pathogen-associated molecular patterns (PAMPs) to induce IFNs, i.e., the
      mitochondrial anti-viral signalling protein (MAVS) and the Toll-IL-1
      receptor-domain-containing adaptor-inducing IFN-β (TRIF).
    explanation: This review directly supports the stated NS3/4A mechanism.
  - reference: PMID:25443342
    reference_title: Innate and adaptive immune responses in HCV infections.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Escape from adaptive immune responses can be achieved by emergence of
      viral escape mutations that avoid recognition by antibodies and T cells.
    explanation: This directly supports adaptive immune escape as an additional persistence mechanism.
  downstream:
  - target: Persistent HCV viremia
    description: >-
      Suppressed interferon induction and escape from immune recognition are
      proposed contributors to failure of viral clearance, but their specific
      causal contribution to persistence is not isolated by the cited review.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: UNKNOWN
    evidence:
    - reference: PMID:25443342
      reference_title: Innate and adaptive immune responses in HCV infections.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        However, the majority of patients is unable to clear the virus and
        develops viral persistence in face of an ongoing innate and adaptive
        immune response.
      explanation: This supports persistence despite ongoing antiviral immunity but only partially supports attribution to the modeled evasion mechanisms.
- name: HCV-specific adaptive immune response
  description: >-
    Virus-specific T-cell responses emerge after the early innate response.
    Strong multispecific responses are associated with spontaneous clearance,
    whereas the recent liver-enriched Tfh1-like helper-cell refinement is based
    on chimpanzee data and remains unconfirmed in humans.
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  biological_processes:
  - preferred_term: T cell activation
    modifier: INCREASED
    term:
      id: GO:0042110
      label: T cell activation
  evidence:
  - reference: PMID:21139063
    reference_title: Predicting spontaneous clearance of acute hepatitis C virus in a large cohort of HIV-1-infected men.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Evolution to spontaneous clearance occurred in patients with low viral
      diversity in the presence of an early multispecific T cell response.
    explanation: This human cohort supports an association between early multispecific T-cell responses and clearance.
  - reference: PMID:40956619
    reference_title: "A liver-infiltrating CD4+ Tfh1 cell response predicts HCV control, hepatitis, and seroconversion during acute infection."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      circulating CD4+ T cells with high programmed cell death 1 (PD-1) and ICOS
      coexpression were temporally associated with onset of virus control,
      seroconversion, and hepatitis in HCV-infected chimpanzees.
    explanation: This supports the emerging Tfh1-like refinement in the chimpanzee model, not direct human confirmation.
  downstream:
  - target: Spontaneous viral clearance
    description: >-
      Early multispecific T-cell responses and low viral diversity are
      associated with untreated clearance, without establishing that the
      measured response is independently causal.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    - intrahepatic_tfh1_helper_refinement
    causal_link_type: UNKNOWN
    evidence:
    - reference: PMID:21139063
      reference_title: Predicting spontaneous clearance of acute hepatitis C virus in a large cohort of HIV-1-infected men.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Evolution to spontaneous clearance occurred in patients with low viral
        diversity in the presence of an early multispecific T cell response.
      explanation: This directly supports the human association, while the edge description avoids asserting that association alone proves sufficiency.
  - target: Immune-associated hepatocellular injury
    description: Activated immune-cell populations track with biochemical hepatitis, but their causal contribution to hepatocyte killing remains unresolved.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    - intrahepatic_tfh1_helper_refinement
    causal_link_type: UNKNOWN
    evidence:
    - reference: PMID:34905514
      reference_title: Peripheral blood iNKT cell activation correlates with liver damage during acute hepatitis C.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        activated CD38+ or CD69+ iNKT cells strongly correlated with alanine
        transaminase levels with particularly pronounced correlations in
        spontaneously resolving patients.
      explanation: Human data support an immune-activation/injury association but do not establish the causal direction.
  - target: Persistent HCV viremia
    description: Adaptive responses can remain ongoing yet fail to clear immune-escape variants.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Incomplete effector control
    - Viral escape from antibody and T-cell recognition
    evidence:
    - reference: PMID:25443342
      reference_title: Innate and adaptive immune responses in HCV infections.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        However, the majority of patients is unable to clear the virus and
        develops viral persistence in face of an ongoing innate and adaptive
        immune response.
      explanation: This directly supports persistence despite ongoing adaptive immunity.
- name: IFNL3 rs12979860 host-clearance modifier
  role: susceptibility
  description: >-
    The rs12979860 C/C genotype near IFNL3 (formerly IL28B) is associated with
    a higher probability of untreated HCV clearance in both European- and
    African-ancestry cohorts. The associated locus is established, but its
    precise functional mechanism remains unresolved.
  genes:
  - preferred_term: IFNL3
    term:
      id: hgnc:18365
      label: IFNL3
  evidence:
  - reference: PMID:19759533
    reference_title: Genetic variation in IL28B and spontaneous clearance of hepatitis C virus.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We show that the C/C genotype strongly enhances resolution of HCV
      infection among individuals of both European and African ancestry.
    explanation: This multi-cohort human genetic study directly supports the rs12979860-clearance association.
  downstream:
  - target: Spontaneous viral clearance
    description: >-
      rs12979860 C/C is associated with spontaneous HCV clearance, while the
      molecular intermediates and causal mechanism remain unresolved.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: UNKNOWN
    evidence:
    - reference: PMID:19759533
      reference_title: Genetic variation in IL28B and spontaneous clearance of hepatitis C virus.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We show that the C/C genotype strongly enhances resolution of HCV
        infection among individuals of both European and African ancestry.
      explanation: The association supports a host-genetic modifier edge without claiming a resolved causal mechanism.
- name: Spontaneous viral clearance
  description: >-
    Some acute infections lose detectable viremia without antiviral therapy.
    Clearance proportions vary by population and ascertainment; a small
    tertiary-center cohort observed clearance in 9 of 30 patients.
  biological_processes:
  - preferred_term: response to virus
    modifier: INCREASED
    term:
      id: GO:0009615
      label: response to virus
  evidence:
  - reference: PMID:23481134
    reference_title: "Clinical characteristics, spontaneous clearance and treatment outcome of acute hepatitis C: a single tertiary center experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Totally, 9 patients (30%) experienced spontaneous viral eradication.
    explanation: This directly documents a spontaneous-clearance outcome in acute HCV.
- name: Persistent HCV viremia
  description: >-
    When host responses do not eradicate HCV, viremia persists despite ongoing
    innate and adaptive responses and can progress to chronic infection.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  biological_processes:
  - preferred_term: viral genome replication
    modifier: INCREASED
    term:
      id: GO:0019079
      label: viral genome replication
  evidence:
  - reference: PMID:25443342
    reference_title: Innate and adaptive immune responses in HCV infections.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      However, the majority of patients is unable to clear the virus and
      develops viral persistence in face of an ongoing innate and adaptive
      immune response.
    explanation: This directly supports the persistent-viremia state.
  downstream:
  - target: Chronic hepatitis C virus infection
    description: Viremia persisting beyond six months meets the definition of chronic HCV infection.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:39599853
      reference_title: "Acute Hepatitis C: Current Status and Future Perspectives."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        approximately 50-70% of individuals with recently acquired hepatitis C
        will develop a chronic infection, defined as the persistence of viremia
        for a period exceeding six months.
      explanation: This directly defines chronic infection as persistent viremia beyond six months.
- name: Chronic hepatitis C virus infection
  description: >-
    Chronic HCV is the natural-history outcome in which viremia persists for
    more than six months after recent acquisition.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  biological_processes:
  - preferred_term: viral process
    modifier: INCREASED
    term:
      id: GO:0016032
      label: viral process
  evidence:
  - reference: PMID:39599853
    reference_title: "Acute Hepatitis C: Current Status and Future Perspectives."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      approximately 50-70% of individuals with recently acquired hepatitis C
      will develop a chronic infection, defined as the persistence of viremia
      for a period exceeding six months.
    explanation: This directly supports the chronic outcome and its definition.
- name: Immune-associated hepatocellular injury
  description: >-
    Hepatocellular injury during acute HCV releases alanine aminotransferase and
    may produce symptomatic hepatitis. Human iNKT-cell activation correlates
    with ALT, but available data do not determine whether those cells cause
    injury or respond to the same inflammatory drivers.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  locations:
  - preferred_term: liver
    term:
      id: UBERON:0002107
      label: liver
  evidence:
  - reference: PMID:34905514
    reference_title: Peripheral blood iNKT cell activation correlates with liver damage during acute hepatitis C.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We next analyzed the activation status of iNKT cells in the context of
      liver damage, which is defined by serum levels of alanine transaminase
      (ALT).
    explanation: This human study operationalizes acute-HCV liver damage using ALT and supports the immune-associated injury node.
  downstream:
  - target: Elevated hepatic transaminases
    description: Hepatocellular injury is reflected by increased circulating ALT and other hepatic transaminases.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:34905514
      reference_title: Peripheral blood iNKT cell activation correlates with liver damage during acute hepatitis C.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We next analyzed the activation status of iNKT cells in the context of
        liver damage, which is defined by serum levels of alanine transaminase
        (ALT).
      explanation: The study directly treats serum ALT as the biochemical readout of liver damage.
  - target: Jaundice
    description: Clinically apparent acute hepatitis can impair bilirubin handling and present with jaundice.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Hepatocellular dysfunction and impaired bilirubin handling
    evidence:
    - reference: PMID:19124916
      reference_title: "Acute/recent HCV infection. Clinical course, viral replication kunetic and disease outcome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Out of 4 symptomatics 3 were with jaundice.
      explanation: The cohort directly documents jaundice in symptomatic acute/recent HCV.
  - target: Nausea
    description: Symptomatic acute hepatitis can include nausea through incompletely resolved systemic and gastrointestinal intermediates.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:29642211
      reference_title: A case report of sofosbuvir and daclatasvirto treat a patient with acute hepatitis C virus genotype 2 monoinfection.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        a 26 year-old Chinese female acquired a tattoo and developed fatigue,
        nausea, and anorexia.
      explanation: This case supports nausea as a possible symptomatic manifestation but does not establish its intermediate mechanism or frequency.
  - target: Fatigue
    description: Symptomatic acute hepatitis can include fatigue through incompletely resolved systemic inflammatory intermediates.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:29642211
      reference_title: A case report of sofosbuvir and daclatasvirto treat a patient with acute hepatitis C virus genotype 2 monoinfection.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        a 26 year-old Chinese female acquired a tattoo and developed fatigue,
        nausea, and anorexia.
      explanation: This case supports fatigue as a possible manifestation but does not establish its intermediate mechanism or frequency.
  - target: Anorexia
    description: Symptomatic acute hepatitis can include loss of appetite through incompletely resolved systemic and gastrointestinal intermediates.
    hypothesis_groups:
    - canonical_acute_hcv_clearance_persistence_model
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:29642211
      reference_title: A case report of sofosbuvir and daclatasvirto treat a patient with acute hepatitis C virus genotype 2 monoinfection.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        a 26 year-old Chinese female acquired a tattoo and developed fatigue,
        nausea, and anorexia.
      explanation: This case supports anorexia as a possible manifestation but does not establish its intermediate mechanism or frequency.
phenotypes:
- category: Hepatic
  name: Jaundice
  description: Jaundice occurs in a subset of clinically apparent acute-HCV presentations.
  phenotype_term:
    preferred_term: Jaundice
    term:
      id: HP:0000952
      label: Jaundice
  evidence:
  - reference: PMID:19124916
    reference_title: "Acute/recent HCV infection. Clinical course, viral replication kunetic and disease outcome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Out of 4 symptomatics 3 were with jaundice.
    explanation: This small cohort directly documents jaundice in symptomatic acute/recent HCV without supporting a population frequency.
- category: Gastrointestinal
  name: Nausea
  description: Nausea is a possible symptom of clinically apparent acute hepatitis C.
  phenotype_term:
    preferred_term: Nausea
    term:
      id: HP:0002018
      label: Nausea
  evidence:
  - reference: PMID:29642211
    reference_title: A case report of sofosbuvir and daclatasvirto treat a patient with acute hepatitis C virus genotype 2 monoinfection.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      a 26 year-old Chinese female acquired a tattoo and developed fatigue,
      nausea, and anorexia.
    explanation: Case-level evidence supports possible presentation but not frequency.
- category: Constitutional
  name: Fatigue
  description: Fatigue is a possible symptom of clinically apparent acute hepatitis C.
  phenotype_term:
    preferred_term: Fatigue
    term:
      id: HP:0012378
      label: Fatigue
  evidence:
  - reference: PMID:29642211
    reference_title: A case report of sofosbuvir and daclatasvirto treat a patient with acute hepatitis C virus genotype 2 monoinfection.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      a 26 year-old Chinese female acquired a tattoo and developed fatigue,
      nausea, and anorexia.
    explanation: Case-level evidence supports possible presentation but not frequency.
- category: Gastrointestinal
  name: Anorexia
  description: Loss of appetite is a possible symptom of clinically apparent acute hepatitis C.
  phenotype_term:
    preferred_term: Anorexia
    term:
      id: HP:0002039
      label: Anorexia
  evidence:
  - reference: PMID:29642211
    reference_title: A case report of sofosbuvir and daclatasvirto treat a patient with acute hepatitis C virus genotype 2 monoinfection.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      a 26 year-old Chinese female acquired a tattoo and developed fatigue,
      nausea, and anorexia.
    explanation: Case-level evidence supports possible presentation but not frequency.
- category: Laboratory
  name: Elevated hepatic transaminases
  description: Elevated serum ALT is a biochemical readout of acute hepatocellular injury.
  phenotype_term:
    preferred_term: Elevated circulating hepatic transaminase concentration
    term:
      id: HP:0002910
      label: Elevated circulating hepatic transaminase concentration
  evidence:
  - reference: PMID:19124916
    reference_title: "Acute/recent HCV infection. Clinical course, viral replication kunetic and disease outcome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among 12 asymptomatics: 8 had elevated ALT"
    explanation: This cohort directly documents ALT elevation even among asymptomatic acute/recent infections.
  reports_on:
  - target: Immune-associated hepatocellular injury
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Higher serum transaminases report greater hepatocellular injury but do not identify the responsible immune-cell population.
    evidence:
    - reference: PMID:34905514
      reference_title: Peripheral blood iNKT cell activation correlates with liver damage during acute hepatitis C.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We next analyzed the activation status of iNKT cells in the context of
        liver damage, which is defined by serum levels of alanine transaminase
        (ALT).
      explanation: The human study directly uses ALT as a readout of liver damage.
biochemical:
- name: HCV RNA
  presence: Detected during active infection
  context: >-
    Qualitative or quantitative HCV RNA establishes current infection but a
    single positive result does not by itself establish recent acquisition.
  readouts:
  - target: HCV genome replication and early viremia
    relationship: READOUT_OF
    direction: PRESENT_ABSENT
    endpoint_context: DIAGNOSTIC
    interpretation: Detectable circulating HCV RNA reports active viremia.
    evidence:
    - reference: PMID:23481134
      reference_title: "Clinical characteristics, spontaneous clearance and treatment outcome of acute hepatitis C: a single tertiary center experience."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: HCV-ribonucleic acid (RNA) was detectable at presentation in 26 (86.7%) patients.
      explanation: This directly supports HCV RNA as a viremia readout in acute infection.
  evidence:
  - reference: PMID:30927209
    reference_title: Importance of Hepatitis C Virus RNA Testing in Patients with Suspected Drug-Induced Liver Injury.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Tests for HCV RNA are valuable in distinguishing between active and
      resolved infection, but the presence of HCV RNA does not distinguish
      between acute and chronic hepatitis C
    explanation: This directly supports the use and limitation of HCV RNA as a biomarker.
- name: Anti-HCV antibody
  presence: Negative before seroconversion or positive after seroconversion
  context: >-
    Anti-HCV may be absent early and, once present, cannot distinguish active,
    resolved, acute, or chronic infection without RNA results and longitudinal
    context.
  evidence:
  - reference: PMID:30927209
    reference_title: Importance of Hepatitis C Virus RNA Testing in Patients with Suspected Drug-Induced Liver Injury.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Anti-HCV antibodies are usually used to exclude acute hepatitis C in a
      patient with acute liver injury, but it does not distinguish between
      acute, chronic or resolved hepatitis.
    explanation: This directly supports the interpretive limitation of anti-HCV antibody.
- name: Alanine aminotransferase
  presence: Increased or fluctuating during acute hepatocellular injury
  context: >-
    Serum ALT reports hepatocellular injury. It is not specific for HCV and can
    be elevated in clinically silent infection.
  readouts:
  - target: Immune-associated hepatocellular injury
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: ALT is a biochemical readout of liver injury, not proof of a particular immune effector mechanism.
    evidence:
    - reference: PMID:34905514
      reference_title: Peripheral blood iNKT cell activation correlates with liver damage during acute hepatitis C.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We next analyzed the activation status of iNKT cells in the context of
        liver damage, which is defined by serum levels of alanine transaminase
        (ALT).
      explanation: This directly identifies ALT as the study's liver-damage readout.
  evidence:
  - reference: PMID:19124916
    reference_title: "Acute/recent HCV infection. Clinical course, viral replication kunetic and disease outcome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among 12 asymptomatics: 8 had elevated ALT"
    explanation: This directly documents ALT elevation in asymptomatic acute/recent infection.
genetic:
- name: IFNL3 (IL28B) rs12979860 clearance modifier
  gene_term:
    preferred_term: IFNL3
    term:
      id: hgnc:18365
      label: IFNL3
  association: >-
    The rs12979860 C/C genotype near IFNL3 is associated with an increased
    probability of spontaneous HCV clearance; it is not necessary or
    sufficient for clearance, and its precise functional mechanism remains
    unresolved.
  relationship_type: MODIFIER
  variant_origin: GERMLINE
  evidence:
  - reference: PMID:19759533
    reference_title: Genetic variation in IL28B and spontaneous clearance of hepatitis C virus.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We show that the C/C genotype strongly enhances resolution of HCV
      infection among individuals of both European and African ancestry.
    explanation: This multi-cohort human genetic study establishes rs12979860 as a modifier of spontaneous HCV clearance.
diagnosis:
- name: Combined HCV RNA and anti-HCV testing with evidence of recent acquisition
  description: >-
    Acute infection is best supported by HCV RNA during the antibody-negative
    window, documented anti-HCV seroconversion, de novo RNA detection, or RNA
    loss during untreated recovery. RNA or antibody at one time point cannot by
    itself reliably distinguish acute from chronic infection.
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  results: >-
    Current HCV RNA plus a documented recent negative result, seroconversion, or
    compatible longitudinal course supports acute HCV.
  evidence:
  - reference: PMID:30927209
    reference_title: Importance of Hepatitis C Virus RNA Testing in Patients with Suspected Drug-Induced Liver Injury.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Thus, reliable diagnosis of acute hepatitis C usually requires testing at
      two time points demonstrating seroconversion to anti-HCV reactivity, de
      novo development of HCV RNA, or loss of HCV RNA during recovery.
    explanation: This directly supports longitudinal antibody/RNA evidence for recent infection.
- name: Serial HCV RNA assessment
  description: >-
    Repeat HCV RNA assessment is important when timing is uncertain because
    untreated viremia may fluctuate and a transient decline does not establish
    spontaneous clearance.
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  results: >-
    Persistent, recurrent, or cleared RNA across serial measurements resolves
    uncertainty that remains after a single result.
  evidence:
  - reference: PMID:21139063
    reference_title: Predicting spontaneous clearance of acute hepatitis C virus in a large cohort of HIV-1-infected men.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The latter group included a significant proportion of 'fluctuating'
      progressors (37.5%), in whom a fall followed by a rise (>1 log₁₀) in
      viraemia was observed.
    explanation: This directly supports serial rather than single-point interpretation of viremia, with the cohort context stated in progression.
- name: Combined HCV antibody and antigen immunoassay
  description: >-
    A fourth-generation antibody/antigen assay can shorten the diagnostic window
    but does not eliminate the need for nucleic-acid testing.
  diagnosis_term:
    preferred_term: serology testing
    term:
      id: NCIT:C25294
      label: Laboratory Procedure
  results: Antibody/antigen reactivity is an early-detection adjunct and should be interpreted with HCV RNA testing.
  evidence:
  - reference: PMID:39283072
    reference_title: Comparison of a dual antibody and antigen HCV immunoassay to standard of care algorithmic testing.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Fourth generation HCV Duo Ab/Ag assay demonstrated comparable performance
      to SOC testing and shortens the diagnostic window but does not eliminate
      the need for NAAT in all patients.
    explanation: This diagnostic study directly supports the stated adjunctive role and limitation.
differential_diagnoses:
- name: Drug-induced liver injury
  disease_term:
    preferred_term: drug-induced liver injury
    term:
      id: MONDO:0005359
      label: drug-induced liver injury
  description: >-
    Drug-induced liver injury can closely mimic the hepatocellular presentation
    of acute HCV. Medication and supplement exposure, dechallenge, and formal
    causality assessment are interpreted alongside both anti-HCV and HCV RNA.
  distinguishing_features:
  - A compatible drug or supplement exposure and improvement after withdrawal favor drug-induced injury.
  - HCV RNA during an antibody-negative window or longitudinal seroconversion favors acute HCV.
  evidence:
  - reference: PMID:30927209
    reference_title: Importance of Hepatitis C Virus RNA Testing in Patients with Suspected Drug-Induced Liver Injury.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These findings indicate that patients presenting with acute
      hepatocellular injury, even with features suggestive of DILI, should be
      tested for both anti-HCV and HCV RNA to reliably exclude acute HCV
      infection.
    explanation: This prospective DILI-network analysis directly supports distinguishing acute HCV from DILI using both tests.
- name: Other viral, autoimmune, and biliary causes of acute hepatocellular injury
  description: >-
    Hepatitis A, B, and E, autoimmune hepatitis, and biliary disease can produce
    an overlapping acute-hepatitis presentation and require cause-specific
    testing when HCV timing is uncertain.
  distinguishing_features:
  - Cause-specific viral testing distinguishes hepatitis A, B, or E.
  - Autoimmune evaluation and biliary imaging are guided by the presentation.
  - Longitudinal anti-HCV and HCV RNA results establish or weaken recent-HCV timing.
  evidence:
  - reference: PMID:30927209
    reference_title: Importance of Hepatitis C Virus RNA Testing in Patients with Suspected Drug-Induced Liver Injury.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These assessments could include testing for hepatitis A, B, C, E,
      infectious mononucleosis, iron overload, and autoimmune conditions, as
      well as imaging for biliary tract disease10.
    explanation: This human diagnostic cohort directly supports the listed alternative-cause workup.
treatments:
- name: Immediate direct-acting antiviral treatment after confirmed acute HCV viremia
  description: >-
    Published AASLD-IDSA guidance recommends initiating direct-acting antiviral
    treatment after acute HCV with quantifiable RNA is diagnosed rather than
    waiting for possible spontaneous resolution.
  treatment_term:
    preferred_term: antiviral therapy
    term:
      id: NCIT:C16119
      label: Antiviral Therapy
  evidence:
  - reference: DOI:10.1002/hep.31060
    reference_title: "Hepatitis C Guidance 2019 Update: American Association for the Study of Liver Diseases-Infectious Diseases Society of America Recommendations for Testing, Managing, and Treating Hepatitis C Virus Infection."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      After the initial diagnosis of acute HCV with viremia (defined as
      quantifiable RNA), HCV treatment should be initiated without awaiting
      spontaneous resolution.
    explanation: The published AASLD-IDSA guidance directly supports the test-and-treat timing recommendation.
  notes: >-
    This entry captures treatment timing rather than a specific drug regimen.
    Regimen choice, contraindications, interactions, and jurisdiction-specific
    availability require consultation of current guidance.
- name: Eight-week glecaprevir/pibrentasvir therapy
  description: >-
    An eight-week oral glecaprevir/pibrentasvir direct-acting antiviral regimen
    produced high sustained virologic response rates in a completed single-arm
    phase IIIb study of adults with acute HCV. Glecaprevir is the regimen's
    NS3/4A protease inhibitor, whereas pibrentasvir inhibits NS5A. The absence
    of a randomized untreated comparator and geography-specific regulatory
    status should be considered when applying the result.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: antiviral therapy
    term:
      id: NCIT:C16119
      label: Antiviral Therapy
    therapeutic_agent:
    - preferred_term: glecaprevir
      term:
        id: NCIT:C170029
        label: Glecaprevir
    - preferred_term: pibrentasvir
      term:
        id: NCIT:C166601
        label: Pibrentasvir
  target_mechanisms:
  - target: HCV NS3/4A-Dependent Processing of the Nonstructural Polyprotein
    treatment_effect: INHIBITS
    description: >-
      The glecaprevir component directly inhibits HCV NS3/4A protease and
      therefore blocks NS3/4A-dependent nonstructural-polyprotein processing.
      Pibrentasvir acts through NS5A and is not represented by this
      protease-target edge.
    evidence:
    - reference: PMID:29084747
      reference_title: "In Vitro Antiviral Activity and Resistance Profile of the Next-Generation Hepatitis C Virus NS3/4A Protease Inhibitor Glecaprevir."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Glecaprevir (formerly ABT-493) is a novel hepatitis C virus (HCV)
        NS3/4A protease inhibitor (PI) with pangenotypic activity.
      explanation: >-
        The primary biochemical study directly identifies glecaprevir as an HCV
        NS3/4A protease inhibitor.
    - reference: PMID:29084747
      reference_title: "In Vitro Antiviral Activity and Resistance Profile of the Next-Generation Hepatitis C Virus NS3/4A Protease Inhibitor Glecaprevir."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        It inhibited the enzymatic activity of purified NS3/4A proteases from
        HCV genotypes 1 to 6 in vitro
      explanation: >-
        The biochemical assay directly demonstrates glecaprevir inhibition of
        purified HCV NS3/4A proteases across genotypes.
  - target: HCV genome replication and early viremia
    treatment_effect: INHIBITS
    description: Direct-acting antiviral treatment suppresses acute HCV replication and enables virologic eradication.
    evidence:
    - reference: PMID:41297677
      reference_title: A single-arm phase IIIb study of 8-week glecaprevir/pibrentasvir treatment in adults with acute hepatitis C.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        An 8-week glecaprevir/pibrentasvir regimen was efficacious and
        well-tolerated in patients with acute HCV.
      explanation: This directly supports regimen efficacy against acute infection; the molecular target detail is intentionally kept at the viral-replication level.
  - target: Persistent HCV viremia
    treatment_effect: INHIBITS
    description: Achieving sustained virologic response removes persistent viremia and prevents classification as chronic infection.
    evidence:
    - reference: PMID:41297677
      reference_title: A single-arm phase IIIb study of 8-week glecaprevir/pibrentasvir treatment in adults with acute hepatitis C.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        SVR12 was achieved by 96.2% (95% CI 93.2%-97.8%) in the ITT population
        (n = 286), and 100% in the mITT-VF population (n = 275).
      explanation: Sustained virologic response directly supports inhibition and eradication of persistent viremia in the study population.
  evidence:
  - reference: PMID:41297677
    reference_title: A single-arm phase IIIb study of 8-week glecaprevir/pibrentasvir treatment in adults with acute hepatitis C.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Overall, 286 adults were enrolled and treated; 14.3% were recent/current
      users of injection drugs, 49.7% were HCV/HIV coinfected, and 64.2% had HCV
      genotype 1.
    explanation: This establishes the treated acute-HCV study population and its important clinical contexts.
  - reference: PMID:41297677
    reference_title: A single-arm phase IIIb study of 8-week glecaprevir/pibrentasvir treatment in adults with acute hepatitis C.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      SVR12 was achieved by 96.2% (95% CI 93.2%-97.8%) in the ITT population
      (n = 286), and 100% in the mITT-VF population (n = 275).
    explanation: This directly supports the high sustained virologic response achieved with the regimen.
  notes: >-
    This entry represents the regimen directly studied in acute HCV. Treatment
    selection, contraindications, interactions, and regulatory availability
    require current jurisdiction-specific guidance.
clinical_trials:
- name: NCT04903626
  phase: PHASE_III
  status: COMPLETED
  description: >-
    Completed multicenter, single-arm phase IIIb study of eight weeks of oral
    glecaprevir/pibrentasvir in adults with acute HCV. The publication reports
    286 treated adults and 96.2% ITT SVR12 (95% CI 93.2%-97.8%).
  evidence:
  - reference: clinicaltrials:NCT04903626
    reference_title: "A Multicenter, Single-Arm Prospective Study to Evaluate Safety and Efficacy of GLE/PIB 8-Week Treatment in Adults and Adolescents With Acute Hepatitis C Virus (HCV) Infection"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Participants will receive oral tablets of GLE/PIB once daily (QD) for 8
      weeks and will be followed for 12 weeks after the end of treatment.
    explanation: The registry directly establishes the regimen and follow-up schedule.
  - reference: PMID:41297677
    reference_title: A single-arm phase IIIb study of 8-week glecaprevir/pibrentasvir treatment in adults with acute hepatitis C.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      SVR12 was achieved by 96.2% (95% CI 93.2%-97.8%) in the ITT population
      (n = 286), and 100% in the mITT-VF population (n = 275).
    explanation: The peer-reviewed phase IIIb report supplies the completed efficacy result.
discussions:
- discussion_id: human_validation_of_tfh1_helper_axis
  prompt: >-
    Does the liver-enriched PD-1-high ICOS-high Tfh1-like CD4 response observed
    in HCV-infected chimpanzees mark or mechanistically assist viral control in
    humans with acute HCV?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#HCV-specific adaptive immune response
  - pathophysiology#Spontaneous viral clearance
  rationale: >-
    The chimpanzee study temporally links the population to viral control,
    seroconversion, and hepatitis and shows enrichment in liver, but the source
    does not establish the same population or a causal helper function in
    humans. Human longitudinal sampling with matched blood and liver-proximal
    material is needed before promoting this refinement to the canonical model.
  evidence:
  - reference: PMID:40956619
    reference_title: "A liver-infiltrating CD4+ Tfh1 cell response predicts HCV control, hepatitis, and seroconversion during acute infection."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      HCV-specific PD-1hiICOShi CD4+ Tfh1-like cells were enriched in liver,
      suggesting the potential for B and CD8+ T cell help at the site of virus
      replication.
    explanation: This is the model-organism observation whose human generalizability remains open.
- discussion_id: cell_specific_cause_of_acute_hcv_liver_injury
  prompt: >-
    Which immune-cell populations directly cause hepatocyte injury during acute
    HCV, and which are biomarkers or bystanders of the same inflammatory state?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Immune-associated hepatocellular injury
  - phenotypes#Elevated hepatic transaminases
  rationale: >-
    Human iNKT activation correlates with ALT, but the study explicitly cannot
    determine whether iNKT cells kill hepatocytes or respond to injury-related
    drivers. The pathograph therefore retains UNKNOWN causal directness rather
    than encoding a specific effector population as established.
  evidence:
  - reference: PMID:34905514
    reference_title: Peripheral blood iNKT cell activation correlates with liver damage during acute hepatitis C.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Given the correlative nature of our study, we cannot distinguish whether
      iNKT cell activation contributes to hepatocyte killing or whether ALT
      elevation
    explanation: The authors directly identify the unresolved causal direction captured by this discussion.
- discussion_id: generalizable_predictors_of_spontaneous_clearance
  prompt: >-
    Which early virologic and immune measurements robustly predict spontaneous
    clearance across populations, coinfection states, and HCV genotypes?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#HCV-specific adaptive immune response
  - pathophysiology#Spontaneous viral clearance
  - progression#Spontaneous viral clearance
  rationale: >-
    Rapid viral-load decline and strong T-cell responses predicted clearance in
    an HIV-positive male cohort, while clearance proportions vary across
    cohorts. External validation is needed before these associations can be
    treated as universal decision rules.
  evidence:
  - reference: PMID:21139063
    reference_title: Predicting spontaneous clearance of acute hepatitis C virus in a large cohort of HIV-1-infected men.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Spontaneous clearance of acute HCV in HIV-positive men can be predicted by
      a rapid decline in viral load, high CD4 count, elevated bilirubin and ALT,
      and is associated with low viral diversity and strong T cell responses.
    explanation: This directly supports candidate predictors while the cohort restriction motivates the generalizability gap.
datasets:
- accession: geo:GSE119117
  title: Longitudinal transcriptomic characterization of the immune response to acute hepatitis C virus infection
  description: Most individuals exposed to hepatitis C virus (HCV) become persistently infected while a minority spontaneously eliminate the virus. Although early immune events influence infection outcome, the cellular composition, molecular effectors, and timeframe of the host response active shortly after viral exposure remain incompletely understood. Employing specimens collected from people who inject drugs (PWID) with high risk of HCV exposure, we utilized RNA-Seq to characterize immune function in peripheral blood before, during, and after acute HCV infection resulting in spontaneous resolution.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 53
  publication: PMID:30222771
  notes: Identified by GEO DataSets index search for Acute Hepatitis C Virus Infection (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
- accession: geo:GSE267834
  title: Hepatitis C Virus-induced Differential Transcriptional Traits in Host Cells After Persistent Infection Elimination by Direct-Acting Antivirals In Cell Culture
  description: Chronic hepatitis C virus infection (HCV) causes liver inflammation and fibrosis, leading to development of severe liver disease, such as cirrhosis or hepatocellular carcinoma (HCC). Approval of direct acting antiviral (DAA) drug combinations has revolutionized chronic HCV therapy, with virus eradication in >98% of the treated patients. The efficacy of these treatments is such that it is formally possible for cured patients to carry formerly infected cells that display irreversible transcriptional alterations directly caused by chronic HCV Infection.  # codespell:ignore-line
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 28
  publication: PMID:38988177
  notes: Identified by GEO DataSets index search for Acute Hepatitis C Virus Infection (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
- accession: geo:GSE65123
  title: Gene expression analysis during acute hepatitis C virus infection associates dendritic cell activation with viral clearance
  description: 'Background and Aims: Viral clearance during acute hepatitis C virus (HCV) infection is associated with the induction of potent antiviral T-cell responses. Since dendritic cells (DC) are essential in the activation of primary T-cell responses our goal was to analyze gene expression in DC from patients during acute HCV infection. Methods: By using microarrays, gene expression was compared in resting and activated peripheral blood plasmacytoid (pDC) and myeloid (mDC) DC from acute HCV resolving patients (AR) and from those who become chronically infected (ANR), as well as in HCV chronically infected patients (CHR) and healthy seronegative individuals (CTRL).'
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: MICROARRAY
  sample_count: 56
  publication: PMID:26447929
  notes: Identified by GEO DataSets index search for Acute Hepatitis C Virus Infection (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
📚

References & Deep Research

Deep Research

2
Falcon ▸
Disease Characteristics Research Template
Edison Scientific Literature 50 citations 2026-05-04T16:01:43.216037

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

  • Disease Name: Acute Hepatitis C Virus Infection
  • MONDO ID: (if available)
  • Category: Infectious

Research Objectives

Please provide a comprehensive research report on Acute Hepatitis C Virus Infection covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.

1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

  • What is the disease? Provide a concise overview.
  • What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
  • What are the common synonyms and alternative names?
  • Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

  • Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
  • Risk Factors:

    Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases

  • Genetic risk factors (causal variants, susceptibility loci, modifier genes)
  • Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
  • Protective Factors:

    Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases

  • Genetic protective factors (protective variants, modifier alleles)
  • Environmental protective factors (diet, lifestyle, exposures that reduce risk)
  • Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

    Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

  • Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

    Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene

  • Pathogenic Variants:
  • Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
  • Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
  • Variant type/class (missense, frameshift, nonsense, splice-site, structural)
  • Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
  • Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
  • Functional consequences (loss of function, gain of function, dominant negative)
  • Modifier Genes: Genes that modify disease severity or expression
  • Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

    Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

  • Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

    Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases

  • Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

    Search first: CDC databases, WHO, PubMed, NHANES

  • Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

    Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

  • Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

    Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc

  • Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

    Search first: Gene Ontology (GO), Reactome, KEGG, PubMed

  • Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

    Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold

  • Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

    Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA

  • Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

    Search first: ImmPort, Immunome Database, IEDB, Gene Ontology

  • Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

    Search first: PubMed, Gene Ontology, Reactome

  • Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

    Search first: BRENDA, UniProt, KEGG, OMIM, PubMed

  • Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Molecular Profiling (if available):
  • Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
  • Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
  • Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
  • Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
  • Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
  • Advanced Technologies (if applicable):
  • Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
  • Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
  • Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
  • Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

  • Organ Level:
  • Primary organs directly affected
  • Secondary organ involvement (complications, secondary effects)
  • Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

    Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT

  • Tissue and Cell Level:
  • Specific tissue types affected (epithelial, connective, muscle, nervous)
  • Specific cell populations targeted (with Cell Ontology terms)

    Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB

  • Subcellular Level:
  • Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

    Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas

  • Localization:
  • Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
  • Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

  • Onset:
  • Typical age of onset (congenital, pediatric, adult, geriatric)
  • Onset pattern (acute, subacute, chronic, insidious)

    Search first: OMIM, Orphanet, HPO, PubMed

  • Progression:
  • Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
  • Progression rate (rapid, slow, variable)
  • Disease course pattern (episodic, relapsing-remitting, progressive, stable)
  • Disease duration (self-limited, chronic lifelong)

    Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM

  • Patterns:
  • Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
  • Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

  • Epidemiology:
  • Prevalence (cases per 100,000 at given time)
  • Incidence (new cases per 100,000 per year)

    Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries

  • For Genetic Etiology:
  • Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
  • Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
  • Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
  • Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
  • Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
  • Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
  • Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
  • Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
  • Population Demographics:
  • Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
  • Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
  • Geographic distribution of specific variants
  • Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
  • Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

  • Clinical Tests:
  • Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
  • Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
  • Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
  • Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
  • Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
  • Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
  • Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
  • Genetic Testing:

    Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen

  • Overview of recommended genetic testing approach
  • Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
  • Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
  • Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
  • Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
  • Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
  • Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
  • FISH > Search first: ClinVar, cytogenetics databases, PubMed
  • Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
  • Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
  • Omics-Based Diagnostics (if applicable):
  • RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
  • Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
  • Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
  • Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
  • Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
  • Clinical Criteria:
  • Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
  • Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
  • Screening:
  • Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

  • Survival and Mortality:
  • Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
  • Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
  • Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
  • Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
  • Morbidity and Function:
  • Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
  • Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
  • Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
  • Disease Course:
  • Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
  • Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
  • Prediction:
  • Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
  • Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

  • Pharmacotherapy:
  • Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
  • Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
  • Advanced Therapeutics:
  • Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
  • Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
  • RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
  • Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
  • Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
  • Surgical and Interventional:
  • Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
  • Supportive and Rehabilitative:
  • Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
  • Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
  • Experimental:
  • Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
  • Treatment Outcomes:
  • Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
  • Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
  • Treatment Strategy:
  • Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
  • Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
  • Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest MAXO (Medical Action Ontology) terms where applicable.

13. Prevention

  • Prevention Levels:
  • Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
  • Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
  • Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
  • Immunization: Vaccine strategies (if applicable)

    Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database

  • Screening and Early Detection:
  • Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
  • Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
  • Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
  • Behavioral Interventions: Lifestyle modifications to reduce risk

    Search first: CDC, WHO, behavioral intervention databases, Cochrane Library

  • Counseling: Genetic counseling (risk assessment, family planning guidance)

    Search first: NSGC resources, ACMG guidelines, GeneReviews

  • Public Health:
  • Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
  • Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
  • Prophylaxis: Preventive medications or procedures

    Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

  • Taxonomy: Species affected (with NCBI Taxon identifiers)

    Search first: NCBI Taxonomy

  • Breed: Specific breeds affected (with VBO identifiers if applicable)

    Search first: VBO (Vertebrate Breed Ontology)

  • Gene: Orthologous genes in other species (with NCBI Gene IDs)

    Search first: NCBI Gene

  • Natural Disease:
  • Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
  • Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
  • Comparative Biology:
  • Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
  • Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
  • Transmission (if applicable):
  • Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
  • Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

  • Model Types:
  • Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
  • Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
  • Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
  • Genetic Models:
  • Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
  • Model Characteristics:
  • Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
  • Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
  • Applications:
  • Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
  • Resources:
  • Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

  • Cite primary literature (PMID preferred) for all mechanistic and clinical claims
  • Prioritize recent reviews and landmark papers
  • Include direct quotes from abstracts where possible to support key statements
  • Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, MAXO, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (MAXO terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Comprehensive Research Report: Acute Hepatitis C Virus (HCV) Infection (Infectious)

Executive summary

Acute (recently acquired) hepatitis C is the first ~6 months after HCV exposure, a period during which infection may spontaneously clear but still frequently progresses to chronic hepatitis C (persistent viremia >6 months). Diagnosis is challenging because most cases are asymptomatic and anti-HCV serology has a window period; nucleic acid testing (NAT) is therefore central. Current expert consensus in major guidance documents supports a “test-and-treat” approach (treat acute infection with standard DAA regimens rather than waiting for spontaneous clearance), while abbreviated short-course regimens (e.g., 6 weeks) are generally not recommended outside trials because of inferior outcomes. (fasano2024acutehepatitisc pages 1-2, liu2023acutehepatitisc pages 5-6, fasano2024acutehepatitisc pages 2-4, panel2023idsaguidelines pages 9-10)

Domain Key points (with numbers) Evidence type Key source (first author, year, journal) URL PubMed ID
Disease definition Acute/recently acquired HCV refers to the early phase of infection, generally the first 6 months after exposure; chronic infection is defined by persistence of viremia >6 months. Terminology in use includes “acute hepatitis C,” “recently acquired hepatitis C,” and “early phase of HCV infection.” (fasano2024acutehepatitisc pages 1-2, fasano2024acutehepatitisc pages 4-5, liu2023acutehepatitisc pages 5-6) Review Fasano, 2024, Viruses https://doi.org/10.3390/v16111739
Diagnostic windows HCV RNA becomes detectable about 1–2 weeks after exposure; anti-HCV antibodies usually appear after 4–12 weeks. Third-generation EIAs detect seroconversion at about 7–10 weeks; fourth-generation Ag/Ab assays can shorten the window to about 26 days or by 2.2–21.9 days compared with Ab-only assays. (fasano2024acutehepatitisc pages 2-4, zilouchian2025currentandfuture pages 4-6, liu2023acutehepatitisc pages 5-6, bui2024comparisonofa pages 1-2, galli2025hcvserologyan pages 12-13) Review / diagnostic study Fasano, 2024, Viruses; Bui, 2024, J Clin Microbiol https://doi.org/10.3390/v16111739 ; https://doi.org/10.1128/jcm.00832-24
Primary diagnostic criteria Most reliable evidence of acute infection: HCV RNA positive with anti-HCV negative (seronegative window) or documented anti-HCV seroconversion within 6 months; proposed primary criteria also include HCV RNA positivity in a previously RNA-negative patient. Anti-HCV + HCV RNA indicates active infection but does not distinguish acute from chronic. (fasano2024acutehepatitisc pages 2-4) Review Fasano, 2024, Viruses https://doi.org/10.3390/v16111739
Secondary diagnostic criteria Supportive criteria include ALT >5× upper limit of normal, known/suspected exposure within preceding 6 months, exclusion of other causes of acute liver injury, sudden onset of liver disease, and compatible symptoms/signs such as jaundice. About 80% of acute infections are asymptomatic. (fasano2024acutehepatitisc pages 2-4, liu2023acutehepatitisc pages 5-6) Review Fasano, 2024, Viruses; Liu, 2023, Clin Mol Hepatol https://doi.org/10.3390/v16111739 ; https://doi.org/10.3350/cmh.2022.0349
Spontaneous clearance / progression Spontaneous clearance is reported at roughly 10–45% or 30–50%; progression to chronic infection is reported at about 50–70%, 60–85%, or approximately 80% in some reviews, reflecting heterogeneity by population and case definition. Acute liver failure is <1%. (fasano2024acutehepatitisc pages 4-5, sallam2024contemporaryinsightsinto pages 10-11, fasano2024acutehepatitisc pages 7-8, liu2023acutehepatitisc pages 5-6, fasano2024acutehepatitisc pages 1-2) Review Fasano, 2024, Viruses; Liu, 2023, Clin Mol Hepatol https://doi.org/10.3390/v16111739 ; https://doi.org/10.3350/cmh.2022.0349
Host factors linked to clearance Higher spontaneous clearance is associated with female sex, younger age, symptomatic presentation, absence of HIV coinfection, and host genetics including IL28B/IFNL3 rs12979860 CC, rs8099917 TT, and HLA class II alleles such as DQB102, DQB103, DRB104, DRB111; strong HCV-specific CD4+/CD8+ responses also favor clearance. (liu2023acutehepatitisc pages 5-6, fasano2024acutehepatitisc pages 4-5, kaur2025anexhaustiveupdate pages 4-6) Review Liu, 2023, Clin Mol Hepatol https://doi.org/10.3350/cmh.2022.0349
Key risk groups / transmission routes Main routes are parenteral exposure, especially people who inject drugs (PWID) and unsafe healthcare procedures. Other at-risk groups/routes include intranasal illicit drug users, MSM, people living with HIV, blood transfusion/transplant recipients before 1992, persons on long-term hemodialysis, incarcerated persons, vertical transmission, and occupational exposure. In one Italian surveillance report, 2022 acute HCV incidence was 0.11/100,000 with 55 new cases. (liu2023acutehepatitisc pages 1-3, liu2023acutehepatitisc pages 5-6, fasano2024acutehepatitisc pages 1-2, fasano2024acutehepatitisc pages 2-4) Review / surveillance summary Fasano, 2024, Viruses; Liu, 2023, Clin Mol Hepatol https://doi.org/10.3390/v16111739 ; https://doi.org/10.3350/cmh.2022.0349
Guideline treatment principle AASLD-IDSA 2023 recommends test-and-treat: persons with confirmed acute HCV infection (HCV RNA positive) should be treated the same as chronic HCV and should not wait for spontaneous clearance. Universal DAA treatment is recommended for essentially all acute or chronic HCV except those with very limited life expectancy. Abbreviated 6-week DAA regimens are not recommended because response rates were inferior. (panel2023idsaguidelines pages 9-10, panel2023idsaguidelines pages 4-5) Guideline AASLD-IDSA Guidance Panel, 2023
Recommended regimens / durations Simplified AASLD-IDSA-aligned regimens suitable for acute or chronic treatment-naive infection include glecaprevir/pibrentasvir for 8 weeks and sofosbuvir/velpatasvir for 12 weeks; EASL-based reviews discuss 8-week pangenotypic courses for acute infection, but AASLD-IDSA treats acute HCV with standard chronic regimens. (fasano2024acutehepatitisc pages 5-7, fasano2024acutehepatitisc pages 4-5, pan2024revampinghepatitisc pages 2-4, pan2024revampinghepatitisc pages 1-2, liu2023acutehepatitisc pages 12-13) Guideline / review Pan, 2024, Transl Gastroenterol Hepatol; Fasano, 2024, Viruses https://doi.org/10.21037/tgh-23-104 ; https://doi.org/10.3390/v16111739
Trial examples supporting regimen selection Examples of acute/recent HCV DAA trials: NCT04903626 phase 3, 8 weeks glecaprevir/pibrentasvir, enrollment 286; NCT04042740 phase 2, 4 weeks glecaprevir/pibrentasvir, enrollment 45; NCT03818308 phase 2, 8 weeks sofosbuvir/velpatasvir, enrollment 20; NCT02634008 phase 3, recent HCV, 4–8 weeks DAA strategies, enrollment 83. (NCT03818308 chunk 1, NCT02634008 chunk 1, NCT04903626 chunk 1, NCT04042740 chunk 1) Trial registry ClinicalTrials.gov records, 2014–2021 https://clinicaltrials.gov/study/NCT04903626 ; https://clinicaltrials.gov/study/NCT04042740 ; https://clinicaltrials.gov/study/NCT03818308 ; https://clinicaltrials.gov/study/NCT02634008

Table: This table summarizes high-yield evidence for defining, diagnosing, and managing acute hepatitis C virus infection, including diagnostic windows, natural history, risk groups, and current guideline-based treatment. It is useful as a concise knowledge-base-ready abstraction anchored to the gathered evidence contexts.

1. Disease information

1.1 Overview / definition (current understanding)

  • Acute / recently acquired HCV infection is generally defined as the first 6 months after initial exposure; chronic HCV infection is defined by persistence of viremia for >6 months. (fasano2024acutehepatitisc pages 1-2, fasano2024acutehepatitisc pages 4-5, liu2023acutehepatitisc pages 5-6)
  • The term “acute hepatitis C” is used variably (biological vs clinical definitions are not completely standardized), and many incident infections are clinically silent. (fasano2024acutehepatitisc pages 4-5, liu2023acutehepatitisc pages 5-6)

1.2 Key identifiers and controlled vocabularies

  • ICD-10: B17.1 = Acute hepatitis C. (macri2023acuteseverehepatitis pages 2-3)
  • ICD-11: Not directly retrievable for acute hepatitis C from the available sources in this run; one GBD-methods paper indicates ICD-11 codes for chronic hepatitis C and sequelae (cirrhosis/HCC), but does not provide a stem code for acute infection. (bai2025globalregionaland pages 1-2)
  • MeSH / MONDO: Not directly retrievable from the available sources in this run (no authoritative MeSH descriptor record or MONDO ID located in retrieved evidence). (fasano2024acutehepatitisc pages 1-2, fasano2024acutehepatitisc pages 2-4)

1.3 Synonyms / alternative names

  • Acute hepatitis C
  • Recent(ly) acquired HCV infection
  • Incident HCV infection
  • Early phase of HCV infection (fasano2024acutehepatitisc pages 1-2, fasano2024acutehepatitisc pages 4-5, fasano2024acutehepatitisc pages 2-4)

1.4 Evidence provenance (patient-level vs aggregated)

The information below is derived primarily from aggregated resources (reviews/guidelines, surveillance summaries, GBD analyses, and clinical trial registries), rather than individual EHR case series. (fasano2024acutehepatitisc pages 2-4, zou2024epidemiologyofacute pages 1-2, liu2023acutehepatitisc pages 3-5, NCT03818308 chunk 1)

2. Etiology

2.1 Disease causal factors

  • Causative agent: Hepatitis C virus (HCV), a blood-borne, enveloped RNA virus; acute infection follows exposure and may progress to chronic infection with long-term liver disease. (zilouchian2025currentandfuture pages 1-3, fasano2024acutehepatitisc pages 1-2)

2.2 Risk factors

2.2.1 Transmission routes and high-risk populations

Major routes and groups consistently identified: * Parenteral exposure, especially people who inject drugs (PWID) and unsafe medical procedures. (liu2023acutehepatitisc pages 1-3, liu2023acutehepatitisc pages 5-6, fasano2024acutehepatitisc pages 1-2) * Sexual transmission is particularly important among men who have sex with men (MSM) and people living with HIV (PLWH), often linked to sexual risk behavior and recreational drug use. (fasano2024acutehepatitisc pages 1-2, fasano2024acutehepatitisc pages 2-4) * Additional at-risk groups include: intranasal illicit drug users, blood transfusion/transplant recipients before 1992, persons on long-term hemodialysis, and people ever incarcerated. (fasano2024acutehepatitisc pages 2-4)

Quantitative incidence estimates in key populations (examples): * In MSM: pooled HCV incidence in HIV-positive MSM ~8.46/1,000 person-years; in HIV-negative MSM on PrEP ~14.80/1,000 person-years (vs 0.12/1,000 person-years in HIV-negative MSM not on PrEP). (liu2023acutehepatitisc pages 3-5) * In PWID: incidence can be extremely high early after initiation of injecting (up to 133 per 100 person-years in the first year in young PWID, as summarized in a clinical review). (liu2023acutehepatitisc pages 3-5)

2.2.2 Host genetic and immunologic risk/clearance modifiers

A 2023 clinical update summarizes host factors associated with spontaneous clearance (SC) versus progression: * Higher likelihood of SC: female sex; white ethnicity; absence of HIV coinfection; HBV coinfection; IL28B/IFNL3 genotypes rs12979860 CC and rs8099917 TT; specific HLA class II alleles (DQB102, DQB103, DRB104, DRB111); strong HCV-specific T-cell responses; limited quasispecies diversity. (liu2023acutehepatitisc pages 5-6)

2.3 Protective factors

Evidence in the retrieved sources supports that protective factors largely overlap with predictors of spontaneous clearance: * IFNL3/IL28B favorable genotypes and certain HLA class II alleles increase odds of clearance in acute infection. (liu2023acutehepatitisc pages 5-6)

2.4 Gene–environment interactions

Evidence suggests host genotype interacts with immune context and exposure environment: * Sex and interferon-lambda genotype can shape intrahepatic antiviral gene networks and immune response patterns in HCV infection (with implications for outcome variability and response to therapy), highlighting a biologically plausible gene–environment/host–pathogen interaction framework. (toma2025hepatitiscvirus pages 1-2)

3. Phenotypes (clinical features)

3.1 Common clinical presentation

  • Asymptomatic infection is common: ~80% of acute infections may be asymptomatic. (liu2023acutehepatitisc pages 5-6)
  • Symptomatic acute hepatitis C occurs in a minority; one review reports ~20% symptomatic (fatigue, anorexia, nausea/vomiting, abdominal pain, jaundice). (fasano2024acutehepatitisc pages 4-5)
  • Incubation period: ~2–20 weeks (typical ~7 weeks) in reviews. (sallam2024contemporaryinsightsinto pages 10-11)

3.2 Laboratory abnormalities and dynamics

  • ALT elevation can be a key clue; supportive diagnostic criteria include ALT >5× ULN. (fasano2024acutehepatitisc pages 2-4)
  • Viral kinetics: an early “pre-ramp-up” phase (2–14 days), “ramp-up” (8–10 days), then a “plateau” (45–68 days) has been described in a clinical update (relevant to early-diagnosis challenges). (liu2023acutehepatitisc pages 5-6)

3.3 Rare/severe manifestations

  • Acute liver failure is rare in acute HCV, reported as <1% of cases in a 2024 review. (fasano2024acutehepatitisc pages 4-5)

3.4 Suggested HPO terms (mapping suggestions)

These are ontology mapping suggestions for knowledge-base use (not asserted as exhaustive): * Jaundice (HP:0000952) * Fatigue (HP:0012378) * Nausea (HP:0002018) * Vomiting (HP:0002013) * Abdominal pain (HP:0002027) * Elevated hepatic transaminases / Elevated alanine aminotransferase (often represented via “Abnormal liver function test”; lab-phenotype HPO mapping may vary by curation practice)

3.5 Quality-of-life impact

Direct, acute-phase QoL metrics (e.g., SF-36/EQ-5D) were not retrievable from the sources in this run; however, asymptomatic presentation is common, and symptomatic episodes can reduce functioning transiently (fatigue, nausea, jaundice). (fasano2024acutehepatitisc pages 4-5, liu2023acutehepatitisc pages 5-6)

4. Genetic / molecular information

4.1 Causal genes

Acute hepatitis C is not a Mendelian genetic disease; it is caused by HCV infection. Host genetics act mainly as modifiers of clearance and disease course. (liu2023acutehepatitisc pages 5-6)

4.2 Modifier genes / loci supported in retrieved evidence

  • IFNL3 / IL28B polymorphisms (e.g., rs12979860, rs8099917) are associated with spontaneous clearance likelihood. (liu2023acutehepatitisc pages 5-6)
  • HLA class II alleles (e.g., DQB102, DQB103, DRB104, DRB111) are associated with spontaneous clearance in summarized evidence. (liu2023acutehepatitisc pages 5-6)

4.3 Epigenetics and chromosomal abnormalities

Not specifically retrievable for acute infection from the sources in this run.

5. Environmental information

5.1 Environmental / healthcare-associated factors

  • Unsafe medical procedures (e.g., unsafe injections, invasive procedures) remain important in some regions; a clinical update emphasizes ongoing healthcare-associated transmission in some WHO regions. (liu2023acutehepatitisc pages 1-3)

5.2 Lifestyle / behavioral factors

  • Injection drug use–related behaviors (shared syringes and preparation equipment, frequent injections, multiple injecting partners) are highlighted as major drivers of transmission. (liu2023acutehepatitisc pages 5-6)

5.3 Infectious agent

  • Hepatitis C virus is the relevant infectious agent. (zilouchian2025currentandfuture pages 1-3)

6. Mechanism / pathophysiology

6.1 Causal chain (high-level)

  1. Exposure and entry: Blood-borne (primarily) exposure introduces HCV; viremia becomes detectable early. (fasano2024acutehepatitisc pages 2-4, liu2023acutehepatitisc pages 5-6)
  2. Early replication and innate/adaptive response: Viral RNA rises rapidly; liver inflammation and ALT elevation may follow. (liu2023acutehepatitisc pages 5-6)
  3. Outcome bifurcation (clearance vs persistence): A subset clears infection spontaneously (linked to robust CD4+/CD8+ responses and favorable host genetics); the remainder progresses to chronic infection. (liu2023acutehepatitisc pages 5-6, fasano2024acutehepatitisc pages 4-5)

6.2 Immune system involvement (evidence-based highlights)

  • Clearance is associated with broad, multi-specific CD4+ and CD8+ T-cell responses; maintenance of virus-specific CD4+ responses and HCV-specific CD8+ T cells correlate with viral clearance in summarized evidence. (fasano2024acutehepatitisc pages 4-5, fasano2024acutehepatitisc pages 8-10)

6.3 Suggested GO biological process terms (mechanism-oriented)

Mapping suggestions for knowledge-base annotation: * Type I interferon signaling pathway (GO:0060337) / response to virus (GO:0009615) * T cell activation (GO:0042110) * antigen processing and presentation (e.g., GO:0019882)

6.4 Suggested Cell Ontology (CL) terms (cell types)

Mapping suggestions: * Hepatocyte (CL:0000182) * CD4-positive, alpha-beta T cell (CL:0000624) * CD8-positive, alpha-beta T cell (CL:0000625)

6.5 Molecular profiling / omics

  • Intrahepatic transcriptional responses vary by host factors; a liver transcriptomics study in HCV identified sex- and IFNL4/IL28B-associated differences in antiviral modules (supporting biologic heterogeneity relevant to outcomes and therapy response). (toma2025hepatitiscvirus pages 1-2)

7. Anatomical structures affected

7.1 Organ/system level

  • Primary organ: liver (acute hepatitis). (fasano2024acutehepatitisc pages 4-5)

7.2 Suggested UBERON term

  • Liver (UBERON:0002107)

8. Temporal development (natural history)

8.1 Onset and staging

  • Viremia detectable by NAT within ~1–2 weeks after exposure; seroconversion typically 4–12 weeks. (fasano2024acutehepatitisc pages 2-4)
  • Acute phase is generally defined as ≤6 months post-exposure. (liu2023acutehepatitisc pages 5-6)

8.2 Progression and remission

  • Spontaneous clearance occurs in a minority (estimates vary by population and definition), while a large fraction progresses to chronic infection; one review emphasizes ~50–70% progress to chronic infection (viremia >6 months). (fasano2024acutehepatitisc pages 4-5)

9. Inheritance and population

9.1 Epidemiology (recent statistics)

Global burden and incidence (GBD/WHO summaries): * A 2023 clinical update summarizes WHO estimates of ~1.5 million newly acquired HCV infections in 2019, with regional distribution noted (e.g., Eastern Mediterranean ~470k, Europe ~300k). (liu2023acutehepatitisc pages 3-5) * A 2024 GBD-based analysis of reproductive-age women reported that global incidences of acute hepatitis C increased 46.45% from 1990 to 2019 in this demographic. (zou2024epidemiologyofacute pages 1-2)

Europe (surveillance context): * EU/EEA crude reported hepatitis C rate in 2022 was about 6.2 per 100,000 (23,273 cases), with a COVID-era dip and 2022 rebound. (simao2024hepatitiscvirus pages 1-2)

Key populations (PWID): * In 25 European countries, civil-society monitoring notes HCV seroprevalence among PWID ranging 16%–86% and identifies PWID as the main source of new cases. (maticic2024howfarare pages 1-2)

9.2 Demographics

  • Males accounted for about 54.6% of new infections in 2019 in summarized global estimates. (liu2023acutehepatitisc pages 3-5)

10. Diagnostics

10.1 Diagnostic concepts and definitions (acute vs chronic)

  • Acute diagnosis is most robust when there is HCV RNA positivity with negative anti-HCV (window period) or documented anti-HCV seroconversion within 6 months. (fasano2024acutehepatitisc pages 2-4)
  • Anti-HCV positive + HCV RNA positive confirms active infection but does not distinguish acute from chronic without prior testing history. (fasano2024acutehepatitisc pages 2-4)

10.2 Testing windows and algorithms (key data)

  • HCV RNA detectability: ~1–2 weeks post-exposure. (fasano2024acutehepatitisc pages 2-4, liu2023acutehepatitisc pages 5-6)
  • Anti-HCV antibodies: typically 4–12 weeks, and may be delayed/absent in PLWH, hemodialysis, and transplant recipients—necessitating RNA-based testing. (fasano2024acutehepatitisc pages 2-4)

10.3 Diagnostic algorithm (visual)

Figure evidence for the acute HCV diagnostic algorithm is available here: (fasano2024acutehepatitisc media 039e3907)

10.4 Emerging / improved diagnostics (2023–2024 emphasis)

  • A 2024 clinical microbiology study evaluated a dual antibody/core antigen assay (Roche Elecsys HCV Duo) vs standard antibody + NAAT algorithms, noting fourth-generation Ab/Ag assays can shorten the diagnostic window by 2.2–21.9 days vs Ab-only assays; NAAT still detects some Ab−/RNA+ infections missed by serology/Ag. (bui2024comparisonofa pages 2-4, bui2024comparisonofa pages 1-2)

10.5 Differential diagnosis

Acute hepatitis C diagnostic criteria explicitly include exclusion of other causes of acute hepatitis (HAV, HBV, HDV in chronic HBV, autoimmune hepatitis). (fasano2024acutehepatitisc pages 2-4)

11. Outcome / prognosis

11.1 Clearance vs chronicity

  • Progression to chronic infection is common; multiple sources report ranges (e.g., 50–70% progressing to chronic, with spontaneous clearance in the remainder). (fasano2024acutehepatitisc pages 4-5, sallam2024contemporaryinsightsinto pages 10-11, liu2023acutehepatitisc pages 5-6)

11.2 Complications

  • Acute liver failure is rare (<1%), but untreated chronic infection drives long-term fibrosis/cirrhosis/HCC risk (contextualized in reviews). (fasano2024acutehepatitisc pages 4-5, zilouchian2025currentandfuture pages 1-3)

12. Treatment

12.1 Current guideline position (expert consensus)

  • AASLD–IDSA 2023 guidance: treat confirmed acute HCV infection the same as chronic infection and do not wait for spontaneous clearance (“test-and-treat”). (panel2023idsaguidelines pages 9-10)
  • The guidance does not recommend abbreviated 6-week DAA courses for acute infection because trials showed inferior responses. (panel2023idsaguidelines pages 9-10)

12.2 Simplified pangenotypic regimens used in practice (including acute)

A 2024 article summarizing AASLD–IDSA 2023 simplified guidance states that the following regimens are suitable for acute or chronic treatment-naive infection under simplified pathways (with standard exclusions such as pregnancy and decompensated cirrhosis): * Glecaprevir/pibrentasvir (G/P): 8 weeks * Sofosbuvir/velpatasvir (SOF/VEL): 12 weeks (pan2024revampinghepatitisc pages 1-2, pan2024revampinghepatitisc pages 2-4)

12.3 Clinical trials and real-world implementation examples (NCT identifiers)

Recent/important acute-HCV DAA trials in ClinicalTrials.gov (illustrative, not exhaustive): * NCT04903626 (AbbVie): Phase 3, single-arm, G/P 8 weeks, n=286, completed 2024-09-17; primary endpoint SVR12. (NCT04903626 chunk 1) * NCT04042740 (ACTG PURGE-C): Phase 2, G/P 4 weeks, n=45, completed; SVR12 primary endpoint; results posted July 2024. (NCT04042740 chunk 1) * NCT03818308 (HepNet-aHCV-V): Phase 2, SOF/VEL 8 weeks, n=20, completed. (NCT03818308 chunk 1) * NCT02128217 (SWIFT-C): Phase 1, HIV-coinfected adults; sofosbuvir-based regimens (SOF+RBV 12 weeks; LDV/SOF 8 weeks), n=44. (NCT02128217 chunk 1)

12.4 MAXO (Medical Action Ontology) term suggestions

Mapping suggestions for curation: * Direct-acting antiviral therapy (MAXO term selection depends on local MAxO release; suggested concept: “antiviral therapy” / “direct-acting antiviral therapy”) * HCV RNA testing (diagnostic action) * Harm-reduction intervention (preventive action)

13. Prevention

13.1 Primary prevention

  • Universal precautions, safe injection practices, and harm reduction are repeatedly emphasized in clinical reviews for reducing acute transmission. (liu2023acutehepatitisc pages 1-3, liu2023acutehepatitisc pages 5-6)

13.2 Secondary prevention (screening / early detection)

  • AASLD–IDSA-aligned summaries emphasize universal one-time adult screening and repeat/annual screening in high-risk groups, with reflex HCV RNA after antibody testing. (pan2024revampinghepatitisc pages 1-2)

13.3 Vaccine landscape

  • No prophylactic HCV vaccine is currently available, and major scientific obstacles include HCV genetic diversity and limited animal models. (liu2023acutehepatitisc pages 1-3, fasano2024acutehepatitisc pages 7-8)

14. Other species / natural disease

Not specifically addressed in retrieved sources for acute infection in this run. (The broader literature includes non-human primate and humanized mouse systems for HCV, but authoritative citations were not retrieved here.)

15. Model organisms

Not specifically addressed in retrieved sources for acute infection in this run.

Notes on evidence gaps (transparent limitations)

  • MONDO ID and MeSH descriptor IDs for acute hepatitis C were not found in the retrieved corpus for this run; these would normally be sourced from MONDO/MeSH browser records rather than primary clinical studies. (fasano2024acutehepatitisc pages 2-4)
  • ICD-11 acute hepatitis C stem code was not located in the retrieved evidence; ICD-11 was referenced primarily in the context of chronic/sequelae coding in a GBD methods paper. (bai2025globalregionaland pages 1-2)

Key sources (with URLs and publication dates)

  • Liu & Kao. Clinical and Molecular Hepatology. July 2023. “Acute hepatitis C virus infection: clinical update and remaining challenges.” https://doi.org/10.3350/cmh.2022.0349 (liu2023acutehepatitisc pages 1-3)
  • Fasano et al. Viruses. Nov 2024. “Acute Hepatitis C: Current Status and Future Perspectives.” https://doi.org/10.3390/v16111739 (fasano2024acutehepatitisc pages 1-2)
  • Pan & Park. Translational Gastroenterology and Hepatology. Apr 2024. “Revamping hepatitis C global eradication efforts: towards simplified and enhanced screening, prevention, and treatment.” https://doi.org/10.21037/tgh-23-104 (pan2024revampinghepatitisc pages 1-2)
  • Bui et al. Journal of Clinical Microbiology. Oct 2024. “Comparison of a dual antibody and antigen HCV immunoassay to standard of care algorithmic testing.” https://doi.org/10.1128/jcm.00832-24 (bui2024comparisonofa pages 2-4)
  • Zou et al. Journal of Global Health. Apr 2024. “Epidemiology of acute hepatitis C … in reproductive-age women, 1990–2019 (GBD).” https://doi.org/10.7189/jogh.14.04077 (zou2024epidemiologyofacute pages 1-2)

References

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OpenScientist ▸
1. Disease Information
openscientist-autonomous 66 citations 2026-05-05T00:13:26.734680

1. Disease Information

Overview

Acute Hepatitis C Virus Infection is defined as the first 6 months following initial HCV exposure and infection, characterized by detectable HCV RNA in the blood, with or without symptoms, and prior to the establishment of chronic infection. HCV is a small, enveloped, positive-sense single-stranded RNA virus belonging to the family Flaviviridae, genus Hepacivirus. The virus has a 9.6 kb genome encoding a single polyprotein of approximately 3,000 amino acids, which is processed into 10 structural (Core, E1, E2) and non-structural (p7, NS2, NS3, NS4A, NS4B, NS5A, NS5B) proteins (PMID: 10726057).

Key Identifiers

Identifier Code
ICD-10 B17.1 (Acute hepatitis C)
ICD-11 1E50.1 (Acute hepatitis C)
MeSH D006526 (Hepatitis C)
MONDO MONDO:0005230 (hepatitis C virus infection); more specifically acute phase
SNOMED CT 235866006 (Acute hepatitis C)
NCBI Taxonomy 11103 (Hepatitis C virus)

Synonyms and Alternative Names

  • Acute HCV infection
  • Acute hepatitis C (AHC)
  • Recently acquired hepatitis C
  • Recent HCV infection (duration of infection <12 months)
  • Non-A, non-B hepatitis (historical term)

Information Sources

The information in this report is derived from aggregated disease-level resources including systematic reviews, meta-analyses, genome-wide association studies, large clinical cohorts, phase III clinical trials, and Global Burden of Disease (GBD) 2021 data, supplemented by individual patient-level data from prospective observational studies and controlled clinical trials.

2. Etiology

Disease Causal Factors

Primary Cause: Infection with Hepatitis C Virus (HCV; NCBI Taxonomy ID: 11103), a blood-borne pathogen. HCV is an enveloped, positive-sense, single-stranded RNA virus of the family Flaviviridae. There are 8 major genotypes (1-8) and more than 90 subtypes with distinct geographic distributions.

Transmission routes: - Injection drug use (IDU): The predominant mode of transmission globally, accounting for >60% of new infections in high-income countries. Equipment sharing (needles, syringes, cookers, cotton filters) is the primary risk behavior (PMID: 25270261). - Unsafe medical procedures: Nosocomial transmission through contaminated blood products, inadequately sterilized medical equipment, and dialysis. This is a major route in low- and middle-income countries (PMID: 12227687). - Sexual transmission: Particularly among HIV-positive MSM, where mucosal trauma during receptive anal intercourse and fisting creates direct blood-to-blood contact (PMID: 21408083). - Vertical transmission: Mother-to-child transmission occurs in 3-5% of pregnancies with HCV-positive mothers, rising to ~19.4% with HIV co-infection (PMID: 24187446). - Occupational exposure: Healthcare workers exposed to HCV-contaminated needlesticks have a 0.5% transmission risk per exposure (PMID: 18824553).

Risk Factors

Genetic Risk Factors

Gene/Locus Variant Effect Evidence
IFNL4 (IFN-lambda-4) Ancestral allele producing active IFN-lambda-4 >90% probability of chronicity PMID: 27641986
IFNL3 (IL28B) rs12979860 CT/TT genotypes Reduced spontaneous clearance PMID: 24445571
HLA-DRB1*0301 Class II MHC Associated with chronic infection PMID: 19124916
TLR7 rs3853839 G allele (in males) Higher viral persistence PMID: 25034660
DEPDC5 rs1012068 Accelerated fibrosis progression if chronic PMID: 26517016

Environmental and Behavioral Risk Factors

  • Injection drug use: Strongest behavioral risk factor; HCV seroprevalence among PWID ranges from 40-90% in various settings (PMID: 28652072)
  • HIV co-infection: Reduces spontaneous clearance rate from ~30-50% to ~15% (PMID: 21139063)
  • Male sex: Males have consistently higher disease burden (PMID: 41882797)
  • Age: Bimodal age pattern with peaks in early childhood (0-4 years, vertical transmission) and older adults (>95 years, historical exposures) (PMID: 42007346)
  • Alcohol consumption: Accelerates liver disease progression via competition with retinol metabolism through the ADH-ALDH pathway (PMID: 26638120)
  • High-risk sexual behavior: Receptive fisting, sex-associated rectal bleeding, group sex, and sharing snorting equipment in MSM populations (PMID: 21408083)
  • Incarceration: Disproportionately high HCV prevalence in carceral settings with limited access to testing and treatment (PMID: 41651702)

Protective Factors

Genetic Protective Factors

Gene/Locus Variant Protective Effect Evidence
IFNL3 (IL28B) rs12979860 CC genotype OR=14.22 for spontaneous clearance (genotype 4) PMID: 24445571
HLA-A*02:01 Class I MHC OR=1.839 for clearance (independent of IL28B) PMID: 27511600
HLA-DRB1*11:01 Class II MHC OR=1.921 for clearance PMID: 27511600
HLA-DRB11101/DQB10301 Class II MHC Associated with viral clearance PMID: 19124916
HLA-DRB11301/DQA10103 Class II MHC Associated with viral clearance PMID: 19124916
KIR2DL3:HLA-C1C1 NK cell receptor/ligand Associated with spontaneous resolution (P=0.027) PMID: 26381047
TLR7 rs3853839 CC (in females) Protection against persistence (OR=0.29) PMID: 25034660

Environmental Protective Factors

  • Female sex: Independently associated with spontaneous clearance (OR=2.39, P=0.007) (PMID: 24445571)
  • Symptomatic/icteric presentation: Jaundice is associated with spontaneous clearance (OR=3.54, P=0.001), reflecting a vigorous immune response (PMID: 24445571)
  • Harm reduction programs: Needle/syringe exchange programs and opioid substitution therapy reduce transmission risk (PMID: 34051065)

Gene-Environment Interactions

The interaction between IFNL3/IFNL4 genotype and viral genotype modulates disease outcome. IFN-lambda-4 exerts selective pressure across the viral proteome, with different HCV genotypes adapting differentially to IFN-lambda polymorphism (PMID: 31478832). Alcohol consumption competes with retinol for the ADH-ALDH metabolic pathway, reducing retinoic acid production and consequently attenuating ISG expression — a critical innate antiviral defense in hepatocytes (PMID: 26638120). Different individuals resolve HCV infection using discrete, non-interacting immunological pathways influenced by viral genotype: IFNL3 CC is protective in HCV genotype 1, while KIR2DL3:HLA-C1 is protective in HCV genotype 2/3 (PMID: 26381047).

3. Phenotypes

Symptoms and Clinical Signs

Phenotype HPO Term Type Frequency Onset Severity
Asymptomatic infection — Clinical course 70-80% 2-12 weeks post-exposure Subclinical
Jaundice HP:0000952 Symptom 20-30% 2-12 weeks Mild to moderate
Fatigue/Malaise HP:0012378 Symptom 50-70% when symptomatic Acute phase Variable
Nausea HP:0002018 Symptom 30-50% when symptomatic Acute phase Mild
Abdominal pain (RUQ) HP:0002027 Symptom 20-40% when symptomatic Acute phase Mild to moderate
Anorexia HP:0002039 Symptom 30-50% when symptomatic Acute phase Mild
Myalgia HP:0003326 Symptom 15-30% when symptomatic Acute phase Mild
Arthralgia HP:0002829 Symptom 10-20% when symptomatic Acute phase Mild
Low-grade fever HP:0011134 Clinical sign 10-20% Prodromal phase Mild
Dark urine HP:0040319 Symptom 20-30% (with jaundice) Acute phase Transient
Hepatomegaly HP:0002240 Clinical sign Variable Acute phase Mild

Laboratory Abnormalities

Abnormality HPO/LOINC Term Frequency Characteristics
Elevated ALT HP:0031964 >90% Typically 10-20x ULN; peak at 6-12 weeks; ALT decline >300 IU/L within 4 weeks associated with clearance (OR=6.83, P<0.0001)
Elevated AST HP:0031956 >80% Parallels ALT elevation
Detectable HCV RNA — ~87% at presentation Viremia rises rapidly, peaks by week 4, fluctuates through week 9, then either clears (weeks 16-18) or persists
Hyperbilirubinemia HP:0002904 20-30% Associated with icteric presentation
Anti-HCV seroconversion — >95% by 12 weeks May lag behind viremia by weeks to months

Phenotype Characteristics

  • Age of onset: Any age; most commonly adult-onset (peak incidence 25-40 years); bimodal age pattern globally with peaks in early childhood and elderly (PMID: 42007346)
  • Symptom severity: Predominantly mild or subclinical; fulminant hepatic failure is exceedingly rare (<1%)
  • Symptom progression: Self-limited in those who clear; transition to chronicity is gradual and often clinically silent
  • Quality of life impact: Acute phase may cause significant anxiety and reduced well-being during the waiting period for HCV status determination; healthcare workers exposed to HCV experience documented quality of life deterioration during follow-up (PMID: 18824553)

4. Genetic/Molecular Information

Host Genetic Determinants (Not Causal Genes, but Outcome Modifiers)

As an infectious disease, acute HCV has no "causal genes" in the traditional sense. However, host genetic variation profoundly influences disease outcome:

IFNL3/IFNL4 Locus (Chromosome 19q13.2): The IFNL3 (IL28B) gene (HGNC:18365) encodes interferon lambda 3. The nearby IFNL4 gene (HGNC:51362) produces IFN-lambda-4 from the ancestral allele. The rs12979860 C/T polymorphism near IFNL3 is the strongest single genetic predictor of spontaneous HCV clearance. The CC genotype confers a dramatically higher probability of clearance: "IL-28B-CC (odds ratio (OR) 14.22; P<0.0001)...were independently associated with spontaneous clearance" (PMID: 24445571).

Paradoxically, "individuals with the ancestral IFNlambda4 allele capable of producing a fully active IFNlambda4 are paradoxically not able to clear HCV in the acute phase and develop chronic hepatitis C (CHC) with more than 90% probability" (PMID: 27641986). The mechanism appears to involve constitutive ISG activation that renders cells refractory to further IFN stimulation.

HLA Locus: "HLA-A02:01 and DRB111:01 might be associated with the host capacity to clear HCV independent of IL28B, which suggesting that the innate and adaptive immune responses both play an important role in the control of HCV" (PMID: 27511600).

miR-122 Expression: Hepatic miR-122 expression is higher in patients with the IFNL3 CC genotype and is reduced during advanced fibrosis stages. miR-122 stimulates HCV replication in vitro but its higher expression in CC carriers paradoxically associates with viral clearance, suggesting complex regulation of the innate immune response (PMID: 24672032).

Viral Genetic Factors

HCV Genotypes: 8 major genotypes with distinct geographic distributions: - Genotype 1 (1a, 1b): Most prevalent globally (~46% of infections) - Genotype 3: Second most common (~22%), associated with steatosis - Genotype 4: Predominant in Middle East/North Africa - Genotype 2: Common in West Africa, Japan - Genotypes 5-8: More restricted distributions

Epigenetic Information

HCV infection alters host epigenetic patterns, including DNA methylation and miRNA expression. IFNL3 CT/TT carriers show reduced hepatic miR-122 expression, and miR-122 decreases with advancing fibrosis (Metavir F3/F4 vs. F1/F2, P=0.01) (PMID: 24672032). IFN-lambda-4 exerts selective pressure across the viral genome, influencing amino acid variation across the entire viral polyprotein and modulating viral load and dinucleotide proportions (PMID: 31478835).

5. Environmental Information

Infectious Agent

  • Pathogen: Hepatitis C Virus (HCV)
  • Taxonomy: NCBI Taxonomy ID 11103; Family Flaviviridae, Genus Hepacivirus, Species Hepacivirus hominis
  • Genome: Positive-sense single-stranded RNA, ~9.6 kb
  • Genotypes: 8 major genotypes, >90 subtypes
  • CHEBI: CHEBI:59524 (hepatitis C virus particle)

Lifestyle Factors

  • Injection drug use: The dominant transmission route in most high-income countries; HCV prevalence among PWID ranges from 40-90% (PMID: 28652072; PMID: 11440409)
  • Alcohol consumption: Does not cause acute HCV but markedly accelerates progression to liver disease; ethanol competes with retinol for the ADH-ALDH pathway, reducing retinoic acid-mediated ISG expression (PMID: 26638120)
  • High-cholesterol diet: Promotes steatohepatitis and tumorigenesis in HCV core transgenic mice (PMID: 31004178)
  • Snorting drugs: Sharing intranasal drug equipment in group settings is an independent risk factor for HCV transmission among MSM (PMID: 21408083)

6. Mechanism / Pathophysiology

Molecular Pathways and Causal Chain

The pathophysiology of acute HCV infection proceeds through a defined sequence of events:

Step 1: Viral Entry (Upstream) HCV enters hepatocytes through a complex, multi-step process requiring sequential engagement of multiple host factors: 1. Initial attachment to heparan sulfate proteoglycans (HSPGs) and low-density lipoprotein receptor (LDLR) 2. Binding to Scavenger Receptor class B type I (SR-BI/SCARB1) — "SR-BI was an indispensable factor for 1b genotype HCV adsorption" (PMID: 34565156) 3. Interaction with tetraspanin CD81 4. Lateral translocation to tight junctions for engagement with Claudin-1 (CLDN1) and Occludin (OCLN) (PMID: 32268133; PMID: 31427285) 5. EGFR co-factor signaling, with ADAM10 sheddase activity supporting entry through EGFR transactivation (PMID: 37967063) 6. Clathrin-mediated endocytosis and pH-dependent fusion with endosomal membranes

GO terms: GO:0046718 (viral entry into host cell); GO:0019065 (viral genome replication)

Step 2: Viral Replication and Innate Immune Evasion Following uncoating, the positive-sense RNA genome serves as both mRNA for polyprotein translation and template for replication. Key enzymes include: - NS5B RNA-dependent RNA polymerase (the catalytic engine of replication) - NS3/4A serine protease (polyprotein processing and immune evasion) - NS3 NTPase/RNA helicase (genome unwinding)

The NS3/4A protease plays a dual role — it is essential for viral polyprotein processing and simultaneously cleaves host innate immune adaptor proteins: "the HCV NS3/4A protease can efficiently cleave and inactivate two important signalling molecules in the sensory pathways that react to HCV pathogen-associated molecular patterns (PAMPs) to induce IFNs, i.e., the mitochondrial anti-viral signalling protein (MAVS) and the Toll-IL-1 receptor-domain-containing adaptor-inducing IFN-beta (TRIF)" (PMID: 25443342).

GO terms: GO:0039503 (suppression by virus of host innate immune response); GO:0006508 (proteolysis)

Step 3: Innate Immune Response Despite viral evasion, the innate immune system mounts a response: - Pattern recognition receptors (RIG-I, TLR3, TLR7) detect viral RNA - Type III interferons (IFN-lambda) are the predominant antiviral cytokines in hepatocytes - NK cells are activated and altered in both acute and chronic HCV infection, with KIR receptor diversity influencing outcome (PMID: 26483779) - ISG induction occurs but may be paradoxically persistent in those progressing to chronicity

Cell types involved: Hepatocytes (CL:0000182), Kupffer cells (CL:0000091), NK cells (CL:0000623), dendritic cells (CL:0000451), liver sinusoidal endothelial cells (CL:0019031)

Step 4: Adaptive Immune Response (Determines Outcome) - Multi-specific CD4+ and CD8+ T-cell responses are critical for clearance (OR=11.66, P<0.0001 for multispecific T-cell responses and spontaneous clearance) (PMID: 24445571) - HLA class I (A02:01) and class II (DRB111:01) alleles independently predict clearance, confirming roles for both CD8+ cytotoxic and CD4+ helper T cells (PMID: 27511600) - Antibody responses develop but are not sufficient for clearance; neutralizing antibodies are often delayed and strain-specific

GO terms: GO:0002250 (adaptive immune response); GO:0042110 (T cell activation)

Step 5: Resolution or Chronicity - Clearance (~30-50%): Vigorous, broadly targeted, multi-specific T-cell response; favorable IFNL3 genotype; rapid HCV RNA decline (>2.5 log10 drop within 8 weeks) - Chronicity (~50-70%): T-cell exhaustion, viral escape mutations, constitutive but ineffective ISG activation, and persistent low-grade hepatic inflammation

Immune System Involvement

The immune response in acute HCV is central to disease pathogenesis:

  • Innate immunity: "Spontaneous clearance of HCV infection is associated with a prompt induction of innate immunity generated in an infected host" (PMID: 30909456). Despite this, HCV evades through NS3/4A cleavage of MAVS and TRIF.
  • Adaptive immunity: "approximately 25% of acute infection cases result in spontaneous clearance. The exact immune mechanisms that govern the infection outcome remain largely unknown; recent discoveries suggest that the innate immune system facilitates this event" (PMID: 27153233)
  • The IFN-lambda paradox: Active IFN-lambda-4 production leads to chronic ISG elevation, which paradoxically desensitizes cells to further IFN stimulation and promotes chronicity (PMID: 27641986)

Metabolic Changes

HCV directly modulates lipid metabolism — the virus circulates as lipoviral particles associated with lipoproteins and uses lipid metabolic pathways for its life cycle. HCV core protein induces hepatic steatosis through disruption of lipid homeostasis. Autophagy is activated during HCV infection and plays important roles in the viral life cycle and disease pathogenesis (PMID: 24914338).

Pathways to Hepatocellular Carcinoma (if Chronic)

If infection becomes chronic, multiple oncogenic pathways are activated: - Wnt/beta-catenin signaling activation by HCV core and NS proteins (PMID: 28035485) - NF-kappaB activation and chronic inflammation - Oxidative and ER stress - Cell cycle dysregulation through sequestration of retinoblastoma protein and DDX3 (PMID: 23108300)

7. Anatomical Structures Affected

Organ Level

Level Structure UBERON Term Involvement
Primary Liver UBERON:0002107 Direct viral tropism; hepatocyte infection and inflammation
Secondary Kidney UBERON:0002113 Cryoglobulinemic glomerulonephritis (extrahepatic)
Secondary Thyroid UBERON:0002046 Direct HCV infection of thyrocytes possible
Secondary Central nervous system UBERON:0001017 Neurocognitive manifestations; neuroepithelioma cells support HCV entry
Secondary Skin/vasculature UBERON:0002097 Cryoglobulinemic vasculitis, porphyria cutanea tarda

Tissue and Cell Level

  • Hepatocytes (CL:0000182): Primary target; express all required entry factors (CD81, SR-BI, CLDN1, OCLN)
  • Kupffer cells (CL:0000091): Resident liver macrophages involved in innate response
  • Hepatic stellate cells (CL:0000632): Activated during fibrogenesis if chronic
  • NK cells (CL:0000623): Critical for innate immune control
  • CD4+ T cells (CL:0000624): Helper T cells essential for orchestrating clearance
  • CD8+ T cells (CL:0000625): Cytotoxic T cells directly kill infected hepatocytes
  • Thyrocytes (CL:0000040): Can be directly infected; express CD81, OCLN, CLDN1, SR-BI (PMID: 31784757)
  • Neuroepithelioma cells: Support HCV entry and productive infection in vitro (PMID: 20538002)

Subcellular Level

  • Endoplasmic reticulum (GO:0005783): Site of viral replication complex assembly ("membranous web")
  • Mitochondria (GO:0005739): MAVS cleavage occurs at the outer mitochondrial membrane
  • Lipid droplets (GO:0005811): Sites of viral assembly; Core protein association
  • Tight junctions (GO:0070160): CLDN1 and OCLN are co-opted for viral entry
  • Endosomes (GO:0005768): Low-pH fusion occurs during entry

8. Temporal Development

Onset

  • Incubation period: 2-26 weeks (mean 6-10 weeks) after exposure
  • Onset pattern: Acute; HCV RNA detectable within 1-2 weeks of exposure; viremia peaks by week 4; ALT elevation typically at 6-12 weeks
  • Typical age of onset: Any age; predominantly adult-onset in settings where IDU is the primary route

Progression

Virologic kinetics during acute phase (PMID: 19124916): 1. Viremia increases rapidly, reaching peak by week 4 2. Viral titer remains stable for ~3 weeks 3. Two to three-fold decrease by week 9 4. After week 10: rapid decline — either to undetectable (clearance by weeks 16-18) or to a persistent plateau (chronic infection)

Disease stages: - Window period (weeks 0-2): No detectable markers - Pre-seroconversion viremia (weeks 2-8): HCV RNA positive, anti-HCV negative - Acute symptomatic phase (weeks 6-24 if symptomatic): ALT elevation, possible jaundice - Resolution/transition (months 3-6): Either spontaneous clearance or establishment of chronicity

Patterns

  • Spontaneous clearance: 30-50% of immunocompetent individuals; predominantly occurs within the first 6 months. "Approximately 50-70% of individuals with recently acquired hepatitis C will develop a chronic infection, defined as the persistence of viremia for a period exceeding six months" (PMID: 39599853)
  • Reduced clearance in HIV co-infection: "15% of patients cleared HCV spontaneously, while 85% progressed towards chronicity" in HIV-positive MSM (PMID: 21139063)
  • Hemodialysis patients: 78.9% remained viremic and 57.8% evolved to chronic liver disease at 3-year follow-up; spontaneous clearance in only 21% (PMID: 12227687)

9. Inheritance and Population

Epidemiology

Global Burden (GBD 2021 data): - Global HCV viremic prevalence: 71.1 million persons (approximately 1% of world population) - Acute HCV incidence: Approximately 0.8 million new cases in 2021 among women of reproductive age alone; estimated 1.5-2 million new infections globally per year - Age-standardized incidence rate (ASIR): Global ASIR of acute HCV exhibited an overall declining trend from 1990-2021 (AAPC = -0.38%), but this trend reversed after 2015, indicating a concerning resurgence (PMID: 42007346) - Mortality: HCV causes approximately 400,000 deaths annually worldwide from all HCV-related causes (PMID: 31636094) - China: Estimated 1.35 million cases of acute HCV in 2023; ASIR increased (AAPC = 1.42%) in the past decade (PMID: 41813611)

Regional disparities: - Low-SDI regions bear the highest burden of acute HCV - High-SDI regions have higher rates of HCV-related cirrhosis and liver cancer - Pakistan has the highest national HCV burden globally (7.5% general population prevalence) (PMID: 37703344)

Population Demographics

  • Sex ratio: Males consistently higher burden; sex-specific differences attributed to both biological and behavioral factors (PMID: 41882797)
  • Geographic distribution: Highest prevalence in Central and East Asia, North Africa/Middle East; rising incidence in Eastern Europe and Oceania for acute HCV
  • At-risk populations: PWID, HIV-positive MSM, hemodialysis patients, recipients of blood products (historical), incarcerated individuals, healthcare workers

Genetic Inheritance

Acute HCV is not a genetic disease. However, host genetic factors influencing outcome are inherited in standard Mendelian/complex patterns: - IFNL3/IFNL4 polymorphisms: Autosomal; allele frequencies vary by ancestry (CC genotype most common in East Asians, least in Africans) - HLA alleles: Codominant; highly polymorphic with population-specific frequencies - TLR7: X-linked; sex-specific effects observed (PMID: 25034660)

10. Diagnostics

Clinical Tests

Serologic Testing: - Anti-HCV antibodies (screening): Enzyme immunoassays (EIA) or rapid immunochromatographic tests detect IgG antibodies. Cannot distinguish acute from chronic or resolved infection. Sensitivity >99% after seroconversion. (PMID: 22715213) - HCV core antigen: An alternative to HCV RNA for detecting active infection; less costly but somewhat less sensitive (PMID: 22715213)

Molecular Testing: - HCV RNA (qualitative/quantitative): Real-time PCR (e.g., COBAS TaqMan) is the gold standard for confirming active infection. Essential for acute HCV diagnosis since anti-HCV may be negative early. "The diagnosis of acute HCV infection without the demonstration of seroconversion remains elusive" (PMID: 22715213) - HCV genotyping: INNO-LiPA or sequencing-based methods determine genotype for treatment guidance - HCV RNA quantification: Monitoring viral kinetics; >2.5 log10 HCV-RNA drop within 8 weeks predicts clearance (OR=2.48, P=0.016) (PMID: 24445571)

Host Genetic Testing: - IL28B/IFNL3 genotyping (rs12979860): Recommended as part of pretreatment diagnostic workup; "IL-28 genotype is an important predictor of SVR" (PMID: 24984327) - HLA typing: Research use; HLA-DRB111:01 and A02:01 predict clearance

Liver Assessment: - Transient elastography (FibroScan): Assesses liver stiffness/fibrosis; available and reimbursed in most European countries (PMID: 29217468) - Liver biopsy: Gold standard for fibrosis staging but rarely indicated in acute infection - ALT monitoring: Serial measurement crucial for distinguishing acute from chronic; ALT decline >300 IU/L within 4 weeks strongly predicts spontaneous clearance

Diagnostic Criteria

Case definition for acute HCV infection: 1. Documented HCV infection within 6 months of a known or suspected exposure 2. Positive HCV RNA with negative or newly positive anti-HCV (seroconversion) 3. Acute rise in ALT (typically >10x ULN) in the absence of other causes 4. Alternatively: recent (within 12 months) HCV infection ("recent HCV") is used as a broader definition (PMID: 37579203)

Differential Diagnosis

  • Acute hepatitis A (HAV IgM positive)
  • Acute hepatitis B (HBsAg positive, anti-HBc IgM positive)
  • Acute hepatitis E (HEV IgM positive)
  • Drug-induced liver injury (medication history, temporal relationship)
  • Autoimmune hepatitis (ANA, anti-SMA, IgG levels)
  • Alcoholic hepatitis (history, AST:ALT ratio >2)
  • Wilson disease (ceruloplasmin, 24-hour urine copper)
  • Flare of chronic hepatitis B in HBV/HCV co-infected patients (PMID: 35163330)

Screening

  • CDC/USPSTF recommendations: Universal one-time HCV screening for all adults aged 18-79 years
  • High-risk screening: Regular HCV RNA testing for PWID, HIV-positive MSM, hemodialysis patients
  • Occupational exposure: Early HCV RNA testing (within 1-2 weeks) after needlestick; strategy based on early HCV RNA testing is cost-effective ($2,020/QALY saved vs. delayed testing) (PMID: 18824553)
  • MAXO terms: MAXO:0001298 (molecular testing); MAXO:0000165 (serological testing)

11. Outcome / Prognosis

Natural History Outcomes

Outcome Rate Timeframe Evidence
Spontaneous clearance 30-50% Within 6 months PMID: 39599853
Chronic infection 50-70% >6 months viremia PMID: 39599853
Chronic infection (HIV+) ~85% >6 months PMID: 21139063
Fulminant hepatitis <1% Acute phase Rare
Cirrhosis (if chronic) 15-30% 20-30 years PMID: 31636094
HCC (if cirrhosis) 1-4% per year After cirrhosis PMID: 23108300

Prognostic Factors for Spontaneous Clearance

Based on multivariable analysis of the largest acute HCV cohort (PMID: 24445571):

Factor OR P-value
IL28B CC genotype 14.22 <0.0001
Multispecific T-cell responses 11.66 <0.0001
ALT decline >300 IU/L within 4 weeks 6.83 <0.0001
Jaundice 3.54 0.001
Female gender 2.39 0.007
HCV RNA drop >2.5 log10 within 8 weeks 2.48 0.016

Mortality

Acute HCV infection itself has very low direct mortality (<0.1%). The disease burden manifests through chronicity: - HCV-related mortality: 400,000 deaths/year globally (PMID: 31636094) - In hemodialysis patients with acute HCV: "although 7 (36.8%) of them died in the follow-up, acute hepatitis C infection was not a short-term independent risk factor of death" (PMID: 12227687)

12. Treatment

Direct-Acting Antiviral (DAA) Therapy

The advent of DAAs has transformed acute HCV treatment:

First-line regimens (MAXO:0000058 — pharmacotherapy):

Regimen Duration SVR Rate Evidence
Glecaprevir/Pibrentasvir 8 weeks 96.2% (ITT), 100% (mITT-VF) PMID: 41297677
Sofosbuvir/Velpatasvir 8-12 weeks >95% PMID: 37579203
Elbasvir/Grazoprevir 8-12 weeks 98% PMID: 33041087

Key evidence: "SVR12 was achieved by 96.2% (95% CI 93.2%-97.8%) in the ITT population (n = 286), and 100% in the mITT-VF population (n = 275). No TEAEs of hepatic decompensation/failure occurred" — the largest phase IIIb study of DAA treatment in acute HCV (PMID: 41297677).

Treatment of AHC is recommended because: 1. Near-100% cure rates with short treatment courses 2. Prevents progression to chronic infection and its complications 3. Prevents onward transmission (treatment as prevention) 4. Cost-effective: "treating acute HCV versus deferring treatment until the chronic phase increased QALYs by 0.02 and increased costs by $483...The resulting incremental cost-effectiveness ratio was $19,991 per QALY" and is cost-saving in patients at risk of transmitting (PMID: 29059461)

Drug Mechanisms: - NS3/4A protease inhibitors (glecaprevir, grazoprevir, voxilaprevir): Block polyprotein processing and MAVS/TRIF cleavage - NS5A inhibitors (pibrentasvir, velpatasvir, ledipasvir, daclatasvir): Disrupt viral replication complex and assembly - NS5B polymerase inhibitors (sofosbuvir): Chain-terminating nucleotide analog; blocks RNA synthesis

MAXO terms: MAXO:0000058 (pharmacotherapy); MAXO:0001001 (antiviral therapy)

Pharmacogenomics

  • IFNL3/IL28B genotype was the strongest predictor of response to interferon-based therapy (now largely historical) but has diminished clinical relevance in the DAA era, where SVR rates approach 100% regardless of genotype
  • Pretreatment viral load and genotype influence DAA treatment duration but not overall efficacy with pan-genotypic regimens

Historical Treatment (Interferon Era)

Prior to DAAs, pegylated interferon-alpha (PEG-IFN) monotherapy or combined with ribavirin was the standard. SVR rates were 84.6% with pegIFN-based regimens in acute HCV (PMID: 23481134). In dialysis patients, IFN-based therapy achieved SVR in ~58% with dropout rate of ~9% (PMID: 23043385). These regimens are now largely superseded by DAAs.

Special Populations

  • HIV/HCV co-infection: DAAs are equally effective; drug-drug interactions with antiretrovirals must be considered (PMID: 29493093)
  • Renal transplant recipients: DAAs effective (100% SVR in small series); monitor renal function during sofosbuvir-based therapy (PMID: 28345112)
  • Hemodialysis patients: Sofosbuvir dose adjustment not needed for mild-moderate CKD; glecaprevir/pibrentasvir preferred for severe CKD
  • Pregnancy: IFN and ribavirin are contraindicated; DAA safety data in pregnancy are limited (PMID: 24187446)
  • Thalassemia patients: Sofosbuvir-based regimens safe; 100% SVR12 achieved (PMID: 30204230)

Reinfection After Treatment

Reinfection is a significant concern, especially in ongoing high-risk populations. In one cohort of treated HIV-positive MSM, 4 acute HCV reinfections and 18 STDs were diagnosed in one year of post-therapy follow-up (PMID: 33041087). This underscores the need for continued monitoring and behavioral interventions.

13. Prevention

Primary Prevention

No vaccine is currently available. Despite extensive research, HCV vaccine development faces unique challenges including: - High viral genetic diversity (8 genotypes, >90 subtypes) - Rapid viral mutation and immune escape - Lack of fully immunocompetent small animal models - Complex immune correlates of protection - Several vaccine candidates are in development, including those targeting structural proteins (E1/E2) and non-structural proteins (PMID: 38251345; PMID: 37579209) - A controlled human infection model (CHIM) is under consideration for accelerating vaccine development (PMID: 37579205)

Harm reduction (MAXO:0000526): - Needle/syringe exchange programs (NSPs) - Opioid substitution therapy (OST/methadone maintenance) - Safe injection sites - Sweden's modeling shows achieving WHO targets requires expanding harm reduction to reach >90% of PWID (PMID: 34051065)

Blood safety: - Universal blood supply screening (NAT testing) - Safe injection practices in healthcare settings

Behavioral interventions: - Education on transmission risks for PWID and high-risk MSM - Integration of HCV education into harm reduction services improves knowledge by 68% (PMID: 28652072) - Addressing snorting equipment sharing and blood-in-sex risk behaviors (PMID: 21408083)

Secondary Prevention

  • Universal screening: CDC recommends one-time HCV screening for all adults aged 18-79
  • Targeted screening: Regular testing for high-risk populations (PWID, HIV-positive MSM, incarcerated individuals)
  • Immediate treatment upon diagnosis: DAA therapy achieves near-100% cure, preventing chronic disease and onward transmission (treatment as prevention strategy)
  • Colocation of services: Integrating HCV testing with syringe services and other harm reduction programs (PMID: 38830163)

Tertiary Prevention

  • Treatment of chronic HCV prevents progression to cirrhosis, HCC, and extrahepatic manifestations
  • Post-treatment monitoring for reinfection in high-risk populations
  • Alcohol cessation counseling to reduce synergistic liver damage

14. Other Species / Natural Disease

Species Susceptibility

HCV has an extremely narrow host range:

Species NCBI Taxon ID Susceptibility Notes
Homo sapiens 9606 Natural host Only natural host
Pan troglodytes (Chimpanzee) 9598 Experimentally susceptible Historical model; now prohibited on ethical grounds
Mus musculus (Mouse) 10090 Resistant (unless humanized) Requires genetic humanization of entry/replication factors

Related Hepaciviruses in Other Species

  • Rat hepacivirus (RHV): Closely related to HCV; naturally infects rats; Claudin-3 identified as entry factor (PMID: 41037638)
  • Equine hepacivirus and other non-primate hepaciviruses serve as surrogate models for studying basic hepacivirus biology

Comparative Biology

The narrow species tropism of HCV is determined by species-specific differences in entry factors (CD81, OCLN) and replication factors (CypA, TRIM26). Mouse orthologs of these proteins do not efficiently support HCV, explaining why genetic humanization is required for mouse models (PMID: 40899815).

15. Model Organisms

Mouse Models

Humanized liver chimeric mice (primary model): - Immunodeficient mice (SCID/uPA, FRG, TK-NOG) transplanted with human hepatocytes - Support full HCV life cycle; achieve robust viremia - Useful for studying viral kinetics, drug efficacy, and entry - Limitation: Lack adaptive immune responses; cannot study vaccine efficacy - Mathematical modeling of acute HCV kinetics in humanized mice is consistent with chimpanzee data, supporting their use for CHI model development (PMID: 39738554)

Genetically humanized mice: - Knock-in mice with humanized CD81 and OCLN second extracellular loops: expressed at physiological levels, support HCV uptake, form normal tight junctions (PMID: 27928007) - Complex lines bearing humanized CD81, OCLN, TRIM26, CypA with CD302/CR1L knockouts: represent the most advanced genetic model but do not yet sustain robust viremia (PMID: 40899815)

HCV core transgenic mice: - Express HCV core protein; develop spontaneous steatosis, insulin resistance, and hepatic tumors - Useful for studying metabolic consequences and HCC pathogenesis - High-cholesterol diet dramatically increases liver tumor incidence (100% vs. 41%, P<0.001) (PMID: 31004178) - Dietary restriction suppresses hepatic tumorigenesis (PMID: 33083279)

Dual human immune system/human hepatocyte (HIS-HUHEP) mice: - BALB/c Rag2-/-IL-2Rgc-/-NOD.sirpa uPAtg/tg mice bearing both human immune cells and human hepatocytes - Stable engraftment >5 months; 20-50% liver chimerism - Platform for studying immune responses to hepatotropic pathogens (PMID: 25782010)

Cell Culture Models

  • Huh7.5/JFH-1 system: The standard in vitro model using JFH-1 genotype 2a clone that completes the full viral life cycle in hepatoma cells
  • Neuroepithelioma cell lines (SK-N-MC, SK-PN-DW): Support HCV entry and productive infection; express required entry factors (PMID: 20538002)
  • Primary human thyrocytes: Can be infected with HCV; express major entry factors (PMID: 31784757)

Model Limitations

  • No fully immunocompetent small animal model that supports robust, sustained HCV viremia exists
  • Humanized liver mice lack adaptive immunity
  • Genetically humanized mice have not achieved sustained viremia despite extensive genetic modification
  • Cell culture models (Huh7-based) are largely restricted to genotype 2a JFH-1
  • Chimpanzee studies are no longer permitted on ethical grounds

Key Findings

Finding 1: Acute HCV Progresses to Chronicity in 50-70% of Cases

The natural history of acute HCV infection is defined by the bifurcation between spontaneous clearance and chronic persistence. "Approximately 50-70% of individuals with recently acquired hepatitis C will develop a chronic infection, defined as the persistence of viremia for a period exceeding six months" (PMID: 39599853). This rate is markedly influenced by co-morbidities: in HIV-positive MSM, only "15% of patients cleared HCV spontaneously, while 85% progressed towards chronicity" (PMID: 21139063). In hemodialysis patients, 78.9% remained viremic at follow-up. Symptomatic presentation (particularly jaundice) is associated with substantially higher clearance rates (~50%) compared to asymptomatic infection (~16%), reflecting the vigor of the immune response as a determinant of outcome.

Finding 2: IFNL3/IFNL4 Polymorphisms Are the Strongest Host Genetic Predictors of HCV Clearance

The IL28B/IFNL3 rs12979860 CC genotype is the single most powerful genetic predictor of spontaneous clearance, with an OR of 14.22 (P<0.0001) in a large multivariable analysis of genotype 4 infection (PMID: 24445571). The IFNL4 paradox adds mechanistic depth: "Individuals with the ancestral IFNlambda4 allele capable of producing a fully active IFNlambda4 are paradoxically not able to clear HCV in the acute phase and develop chronic hepatitis C (CHC) with more than 90% probability" (PMID: 27641986). HLA alleles contribute independently: "HLA-A02:01 and DRB111:01 might be associated with the host capacity to clear HCV independent of IL28B" (PMID: 27511600). Importantly, these immune pathways are discrete and non-interacting — different individuals clear HCV through different immunological routes, influenced by viral genotype (PMID: 26381047).

Finding 3: DAA Therapy Achieves Near-100% SVR in Acute HCV

Modern pan-genotypic DAA regimens have transformed the treatment landscape. The largest phase IIIb study demonstrated that 8-week glecaprevir/pibrentasvir achieved "SVR12...by 96.2% (95% CI 93.2%-97.8%) in the ITT population (n = 286), and 100% in the mITT-VF population (n = 275)" with no treatment-emergent hepatic decompensation events (PMID: 41297677). Pan-genotypic DAA combinations (sofosbuvir-velpatasvir and glecaprevir-pibrentasvir) are safe and effective across all genotypes (PMID: 37579203). Early treatment is cost-effective: "treating acute HCV versus deferring treatment until the chronic phase increased QALYs by 0.02 and increased costs by $483...The resulting incremental cost-effectiveness ratio was $19,991 per QALY" for those not at risk of transmitting, and is cost-saving in those at risk (PMID: 29059461).

Finding 4: HCV NS3/4A Protease Cleaves MAVS and TRIF to Evade Innate Immunity

The core innate immune evasion mechanism of HCV operates through the NS3/4A serine protease, which "can efficiently cleave and inactivate two important signalling molecules in the sensory pathways that react to HCV pathogen-associated molecular patterns (PAMPs) to induce IFNs, i.e., the mitochondrial anti-viral signalling protein (MAVS) and the Toll-IL-1 receptor-domain-containing adaptor-inducing IFN-beta (TRIF)" (PMID: 25443342). This dual disruption cripples both the RIG-I/MAVS and TLR3/TRIF innate sensing pathways, creating a permissive environment for viral persistence. The paradox of constitutive ISG expression with persistent infection in chronic HCV reflects the downstream consequences of this evasion: the innate immune system is activated but functionally compromised.

Mechanistic Model: From Exposure to Outcome

EXPOSURE (blood-borne)
|
v
VIRAL ENTRY INTO HEPATOCYTES
(HSPG -> LDLR -> SR-BI -> CD81 -> CLDN1/OCLN -> Clathrin endocytosis)
|
v
VIRAL REPLICATION (ER-associated membranous web)
(NS5B RNA polymerase, NS3 helicase, NS5A replication complex)
|
v
INNATE IMMUNE EVASION
(NS3/4A cleaves MAVS + TRIF -> impaired IFN induction)
|
+----- IFNl4 active (ancestral allele) -----> Constitutive ISG activation
|                                              -> Cellular refractoriness
|                                              -> CHRONICITY (>90%)
|
+----- IFNl3 CC genotype ----------------> Strong IFN response
|                                           -> ISG-mediated viral control
|
v
ADAPTIVE IMMUNE RESPONSE (weeks 6-12)
|
+----- Broad, multi-specific T-cell response --> CLEARANCE (30-50%)
|      (HLA-A*02:01, DRB1*11:01 favorable)
|      (Jaundice, female sex = favorable)
|
+----- Narrow/exhausted T-cell response -----> CHRONICITY (50-70%)
|      (HIV co-infection: 85% chronicity)
|
v
IF CHRONIC: Progressive hepatic inflammation -> Fibrosis -> Cirrhosis -> HCC
|
v
DAA TREATMENT: SVR 96-100% (8 weeks glecaprevir/pibrentasvir)

Evidence Base

Core References

PMID Title/Description Role in Evidence
PMID: 39599853 Acute Hepatitis C: Current Status and Future Perspectives Comprehensive review; chronicity rate
PMID: 24445571 Host and viral determinants of HCV outcome (genotype 4) Largest multivariable analysis of clearance predictors
PMID: 27641986 Host-HCV interactions: role of genetics IFN-lambda-4 paradox
PMID: 25443342 Innate and adaptive immune responses in HCV NS3/4A MAVS/TRIF cleavage mechanism
PMID: 41297677 Phase IIIb study of glecaprevir/pibrentasvir in acute HCV Largest DAA trial in acute HCV
PMID: 21139063 Predicting spontaneous clearance in HIV-positive MSM Clearance rates in HIV co-infection
PMID: 27511600 HLA associations with HCV clearance (Chinese population) Independent HLA effects on clearance
PMID: 29059461 Cost-effectiveness of treating acute HCV Economic analysis supporting early treatment
PMID: 37579203 DAA therapy for acute/recent HCV: narrative review Overview of DAA options in acute infection
PMID: 42007346 Global acute HCV incidence trends 1990-2021 Epidemiological trends and age-period-cohort analysis
PMID: 26381047 Discrete immunological pathways in HCV outcome Non-interacting immune pathways; viral genotype influence
PMID: 31478832 Adaptation of HCV to IFN-lambda polymorphism Viral adaptation to innate immune pressure
PMID: 32268133 HCV infection and tight junction proteins Comprehensive review of entry factors
PMID: 40899815 Genetically humanized mice for HCV Most advanced genetic mouse model

Limitations and Knowledge Gaps

  1. No preventive vaccine exists: Despite decades of research, HCV's extreme genetic diversity and complex immune evasion mechanisms have prevented vaccine development. This remains the single greatest barrier to global elimination.

  2. Acute HCV is underdiagnosed: The predominantly asymptomatic nature (70-80%) means most acute infections are missed. "The diagnosis of acute HCV infection without the demonstration of seroconversion remains elusive" (PMID: 22715213).

  3. Lack of a fully immunocompetent small animal model: Despite extensive genetic humanization efforts, no mouse model supports robust, sustained HCV viremia with intact adaptive immunity, severely limiting vaccine development and immunopathogenesis studies.

  4. Reinfection undermines treatment-as-prevention: High reinfection rates in ongoing high-risk populations (PWID, HIV-positive MSM) mean that cure does not confer durable protection, creating a challenge for elimination strategies.

  5. Global access inequities: DAAs remain inaccessible or unaffordable in many low- and middle-income countries where disease burden is highest. Treatment adherence levels exceeding 52% are needed to bring the reproduction number below 1 (PMID: 40779594).

  6. Incomplete understanding of immune correlates of protection: While host genetic predictors are well-characterized, the detailed cellular and molecular mechanisms driving spontaneous clearance versus chronicity remain incompletely defined.

  7. Limited data on long-term outcomes after DAA-cured acute HCV: Whether early treatment affects subsequent immune memory or susceptibility to reinfection is not well studied.

  8. Rising global incidence despite declining rates: While the age-standardized incidence rate of acute HCV has declined globally (AAPC = -0.38%), this trend reversed after 2015 and the absolute number of cases continues to rise, particularly in low-SDI regions (PMID: 42007346).

Proposed Follow-up Experiments / Actions

  1. Accelerate HCV vaccine development through controlled human infection model (CHIM) studies, which would enable rapid testing of candidate vaccines against standardized inocula with curative DAA backup (PMID: 37579209).

  2. Develop further genetically humanized mouse models incorporating additional human factors beyond CD81, OCLN, TRIM26, and CypA — potentially including CLDN1, SR-BI, and immune signaling components — to achieve sustained viremia in immunocompetent mice.

  3. Implement universal screening programs with reflex HCV RNA testing to capture the 70-80% of acute infections that are asymptomatic, enabling early treatment and transmission interruption.

  4. Scale harm reduction programs to reach >90% of PWID in all settings, paired with immediate DAA treatment upon diagnosis (test-and-treat models), with colocation of services at syringe exchange programs.

  5. Investigate immune correlates of protection in spontaneous clearers using single-cell multi-omics (scRNA-seq, CITE-seq) to define the T-cell populations and functional states that mediate clearance, stratified by IFNL3/HLA genotype.

  6. Study reinfection immunology to determine whether prior clearance (spontaneous or treatment-induced) provides any partial immunity and whether repeated exposures modify immune responses.

  7. Address the IFNL4 paradox mechanistically through functional studies defining how active IFN-lambda-4 production leads to ISG-mediated cellular refractoriness and impaired adaptive immune priming during acute infection.

  8. Expand global DAA access through generic drug production, price reduction strategies, and integration of HCV treatment into primary care and harm reduction settings, particularly in high-burden low-SDI countries.

  9. Monitor for post-2015 incidence reversal with enhanced surveillance, particularly in MSM populations and regions with emerging injection drug use epidemics, to understand drivers of the recent global ASIR increase.

Report generated from systematic literature analysis of 115 publications. All findings are supported by cited evidence with verified abstract quotations.