Diagnostic advances in viral hepatitis: the discovery of hepatitis C virus and genetic heterogeneity of hepatitis B virus.

The discovery of hepatitis C virus (HCV) and its serological markers represents a new milestone in the history of viral hepatitis and allows a specific diagnosis of viral hepatitis in more than 90 percent of cases. In addition, testing for anti-HCV plays a crucial role in prevention of post-transfusion non-A, non-B hepatitis. The multifaceted spectrum of liver disease associated with hepatitis B virus (HBV) infection, spanning from a healthy carrier state to severe forms of chronic hepatitis, was traditionally attributed to variability of host's antiviral immune response. The finding that a peculiar natural course and response to interferon of chronic hepatitis B is associated with the infection of a defective HBV unable to secrete the "e" antigen (HBeAg-minus) emphasizes the clinical implications of the genetic heterogeneity of hepatitis viruses.