[Diagnosis of type B hepatitis].

Since 1965, when Blumberg discovered the Australia antigen, the hepatitis B surface antigen (HBsAg), the research on viral hepatitis has rapidly progressed. The identification of specific hepatitis B associated antigens and antibodies in blood, and liver tissue, together with the improvement of detection systems, have enhanced our knowledge about the mechanism of liver injury and the natural history of hepatitis B virus (HBV) infection. Now it has been recognized that HBV has no direct cytopathic effect on hepatocytes and that hepatocyte necrosis is associated with the virus induced immunological reaction of the host. From the reaction, there are two types of HBV infection, i.e., transient (acute) and persistent (chronic) infection. In addition to the conventional measurements, such as HBsAg, anti-HBs, anti-HBc, HBeAg, anti-HBe and anti-IgM HBc, recently pre S1, pre S2 antigen/antibody systems and polymerized human albumin receptor and antibody have been developed. The significance of the detection of these antigen/antibody systems was discussed. On the other hand, to determine the presence of HBV, the state of HBV replication or the infectivity directly, HBV associated DNA polymerase and HBVDNA should have been detected. (Very recently, the polymerase chain reaction method has been introduced to detect very small amounts of HBVDNA). In this presentation, the change of these viral markers in various cases was shown, and especially emphasized was anti-IgM HBc in acute hepatitis and HBeAg/Ab status in chronic liver disease. Lastly, the present state of Interferon therapy for type B chronic hepatitis was mentioned.