The clinical significance of hepatitis B virus antigens and antibodies.

There are two well-characterized antigen-antibody systems which relate specificially to viral hepatitis B. Tests for HBsAg and anti-HBs are readily available and of great benefit to the diagnosis, prevention and understanding of hepatitis B. Tests for HBcAg and anti-HBc are still research techniques which requires further development before they can be used at the level of everyday medical practice. HBsAg in an individual indicates that he harbors the virus of hepatitis B; it may be present in the absence of liver disease or be found in association with both acute and chronic type B hepatitis. The presence of HBsAg also suggests that HBV may be causally related to some cases of periarteritis nodosa, chronic glomerulonephritis, and hepatoma. Although HBV is readily transmitted in blood, the major portion of post-transfusion hepatitis now appears to be serologically unrelated to either the hepatitis B virus ("serum") or the hepatitis A virus ("infectious"); the etiology of these cases is currently undetermined. There is increasing evidence that HBV may be transmitted by modes other than blood, but the exact mechanisms of such transmission is not established. The combined transmission of HBV by blood and other routes has resulted in a large number of persistent carriers of HBsAg in the world. There is no current method to alter this carrier state. The hepatitis risk of such persistent carriers to their personal and professional contacts is under investigation.