[Hepatitis viruses].

The existence of five kinds of hepatitis viruses such as hepatitis A, B, C, D and E has been convinced since 1967 when Blumberg discovered hepatitis B virus. The confirmation of virus which induces hepatitis has mainly depended on the measurement of antigen/antibody system. However, in order to grasp the entity of liver disease in more detail, analysis of virus nucleic acid is required. Especially, in case of patients who showed persistent infection of hepatitis B virus or hepatitis C virus, genetical analysis of hepatitis virus is required to make clear the liver disease, to determine the therapeutic method and to predict the prognosis. Recently, there are several reports which suggest the existence of new hepatitis virus that induces acute hepatitis or chronic hepatitis. Among these not determined viruses, GB agent is going to be recognized as a new hepatitis virus (HGV) which provoke hepatitis.