Hepatitis B and C

Hepatitis B virus (HBV) and hepatitis C virus (HCV) both injure hepatocytes, but the usual clinical trajectory is different. HBV is a DNA virus that can leave a stable genetic template, called covalently closed circular DNA, inside the hepatocyte nucleus. Liver injury is driven mainly by the host immune response attacking infected cells rather than by direct viral destruction alone. A strong, coordinated immune response may clear acute HBV. An ineffective response may allow persistent infection and ongoing inflammation. The age at infection changes the risk of chronic HBV dramatically. Infection acquired around birth is highly likely to become chronic, whereas most immunocompetent adults clear acute infection. That is why identifying maternal infection and protecting the newborn promptly are high-priority prevention measures. HCV is an RNA virus with substantial genetic variation. The virus can evade immune recognition, and many infections become chronic. Unlike HBV, there is no effective vaccine for HCV. Chronic HCV may remain clinically silent while fibrosis accumulates over years, eventually causing cirrhosis, portal hypertension, liver failure, or hepatocellular carcinoma. Both viruses can be transmitted through blood. HBV...