Hepatitis C Virus
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Direct answer
Hepatitis C virus, a flavivirus with a positive-sense RNA genome, causes chronic infection in most people who acquire it and is a major cause of cirrhosis and hepatocellular carcinoma. Anti-HCV antibody screens for exposure, but only HCV RNA proves active infection. Direct-acting antivirals now cure the large majority of treated patients, and cure is defined as sustained virological response, meaning undetectable RNA 12 weeks after treatment ends.
What you must remember
- Genome: Enveloped positive-sense single-stranded RNA virus; a high mutation rate produces quasispecies within each patient.
- Genotypes: Six major genotypes (seven or more are now recognised) with many subtypes; genotype 3 is among the most prevalent in India, with genotype 1 also common.
- Genotype 3: Linked with hepatic steatosis and it influences the choice and duration of antiviral therapy.
- Screening: Anti-HCV ELISA detects past or present exposure, and a negative result in a high-risk or immunosuppressed person may need repeat testing.
- Confirmation: HCV RNA by PCR establishes active viraemia, and antibody positivity alone does not.
- Extrahepatic disease: Mixed cryoglobulinaemia, membranoproliferative glomerulonephritis, porphyria cutanea tarda and B-cell non-Hodgkin lymphoma are associations.
- Treatment: Direct-acting antivirals target NS3/4A protease, NS5A and NS5B (sofosbuvir is an NS5B inhibitor); interferon-based therapy has been replaced because the newer drugs are more effective and better tolerated.
- Vaccine: None exists, because of the virus's high mutation rate and diversity across genotypes.
A pathway from antibody to cure
Hepatitis C is managed as a sequence: detect the antibody, confirm the RNA, identify the genotype, then choose the drug. Each step changes the next, so the exam sequence matters.
- Screen with antibody: Anti-HCV ELISA identifies past or present exposure, and a negative result in a high-risk person still needs repeat testing if suspicion persists.
- Confirm viraemia: HCV RNA by PCR shows active infection, which antibody positivity alone cannot establish.
- Genotype the virus: Genotype can guide drug selection and duration, and genotype 3 is particularly relevant in India, although pangenotypic regimens such as sofosbuvir with velpatasvir reduce the need for it.
- Assess the liver: Fibrosis staging by elastography or biopsy, together with screening for hepatocellular carcinoma, decides the urgency of treatment.
- Treat with DAAs: Regimens combine NS5A and NS5B inhibitors, usually for about 8 to 12 weeks depending on genotype and cirrhosis.
- Confirm cure: HCV RNA is checked 12 weeks after treatment; undetectable RNA at that point is sustained virological response, which means cure.
Where the exam tries to catch you
Hepatitis C questions often test what the antibody does and does not tell you, along with the drug era.
- Trap: Calling a positive anti-HCV a current infection. Correct: Antibody shows exposure, and HCV RNA is required to establish active viraemia.
- Trap: Choosing interferon as the modern treatment. Correct: Direct-acting antivirals replaced interferon-based therapy because they are more effective and better tolerated.
- Trap: Assuming a hepatitis C vaccine exists. Correct: No vaccine exists, because the virus is highly variable across genotypes and within each patient.
Frequently asked questions
Which test confirms active hepatitis C infection?
HCV RNA detection by PCR confirms active hepatitis C infection, since anti-HCV antibody shows only past or present exposure. RNA testing is also used to check for cure after treatment.
Why is there no hepatitis C vaccine?
Hepatitis C virus has a high mutation rate and exists as many genotypes and quasispecies within each patient. This diversity makes it very hard to design a vaccine that protects against all variants.
Which hepatitis C genotype is prominent in India?
Genotype 3 is among the most prevalent genotypes in India, and genotype 1 is also common. Genotype 3 is linked with hepatic steatosis and influences the choice of antiviral regimen.
What does sustained virological response mean in hepatitis C?
Sustained virological response means HCV RNA remains undetectable 12 weeks after completing antiviral treatment. It is the accepted measure of cure in hepatitis C, and most patients treated with direct-acting antivirals achieve it.
Which extrahepatic conditions are linked with hepatitis C?
Mixed cryoglobulinaemia, membranoproliferative glomerulonephritis, porphyria cutanea tarda and B-cell non-Hodgkin lymphoma are recognised extrahepatic associations of hepatitis C infection.