Hepatitis B-antigen subtypes in Australia as detected by radioimmunoassay

The distribution of the major subtypes of hepatitis B surface antigen (HBsAg) was examined in asymptomatic white Australian blood donors and patients with liver disease to attempt ot assess the biological significance of these subtypes in this relatively homogeneous Caucasian population. Since previous studies have shown a very low prevalence of HBsAg in white Australians, a highly sensitive solid phase radioimmunoassay (RIA) was developed and used to subtype the antigen. A total of 46 samples of hepatitis B-antigen positive sera, obtained from 21 asymptomatic volunteer blood donors and 25 patients with liver disease, were tested. Sixteen of these 21 asymptomatic carriers were shown to have subtype "ad" whereas only seven of the patients with liver disease had this subtype. This difference was significant (P less than 0.005) and supports the view that subtype "ad" is associated with a carrier state and subtype "ay" with liver disease in Australia.