Which feature best distinguishes Hepatitis B from Hepatitis C in terms of viral persistence and chronic infection patterns?

Explanation

## Chronic Infection Rates: HBV vs HCV **Key Point:** The natural history of chronic infection differs markedly between Hepatitis B and Hepatitis C, with HCV having a much higher propensity for chronicity in adults. ### Hepatitis B Chronicity - **Adults:** 5–10% develop chronic infection (90–95% clear the virus spontaneously) - **Neonates/infants:** 90% develop chronic infection (age-dependent immune tolerance) - Clearance is typically via robust CD8+ T-cell response ### Hepatitis C Chronicity - **Adults:** 70–85% develop chronic infection (only 15–30% spontaneously clear) - **Mechanism:** High viral mutation rate (RNA-dependent RNA polymerase lacks proofreading) allows immune escape - Persistent viremia is the hallmark ### Comparison Table | Feature | Hepatitis B | Hepatitis C | | --- | --- | --- | | Chronic infection rate (adults) | 5–10% | 70–85% | | Genome type | DNA (dsDNA) | RNA (ssRNA, +ve sense) | | Mutation rate | Low | Very high (quasi-species) | | Immune escape | Rare | Frequent | | Clearance mechanism | Strong Th1/CD8+ response | Often inadequate response | **High-Yield:** HCV's high chronicity is due to its error-prone RNA polymerase, which generates antigenic variants faster than the immune system can respond. This is why HCV is often called a "moving target" virus. **Clinical Pearl:** The high chronicity of HCV (70–85%) makes it a major cause of cirrhosis and hepatocellular carcinoma worldwide, despite being less acutely severe than HBV. ### Why This Matters - HBV: Most infected adults recover; chronic HBV is mainly a problem in those infected as infants/children - HCV: Most infected adults progress to chronic infection; screening and early treatment are critical [cite:Harrison 21e Ch 360]