Recent advances in the identification of hepatitis viruses * JULES

Resulting directly from the discovery of virus-related antigens, rapid progress has marked the last decade of viral hepatitis research. The hepatitis B virion has been tentatively identified as a DNA virus with an endogenous DNA polymerase, and new serological markers for type B hepatitis have been discovered. Hepatitis A antigen has been identified on a virus-like particle thought to be the hepatitis A virion. Progressively more sophisticated assays for hepatitis antigens and antibodies have been applied to the study of viral hepatitis epidemiology and biochemicalbiophysical characterization of the agents. Most recently, knowledge learned from such studies has been exploited to develop a prototype non-infectious but immunogenic hepatitis B vaccine using hepatitis B surface antigen (HB,Ag) purified in large quantities from chronic HB,Ag carriers. Especially exciting is the prospect, suggested by serological studies of viral hepatitis, that hepatitis viruses besides hepatitis A and B viruses will be identified.