Hepatitis B antigen subtypes in asymptomatic carriers in the Solomon Islands

Three hundred and fifty-three students attending King George VI School in Honiara, British Solomon Islands Protectorate, were tested by immunodiffusion for hepatitis B surface antigen (HBS Ag). The prevalence of HB Ag was 13% and the antigen was found more frequently in males. Twenty-seven samples which contained high titers of antigen were subtyped to define those subtype combinations present in the BSIP. The most frequent antigen was adr+yw-. This combination is also common in Thailand and Japan. The second most prevalent combination was ayw+dr-. The antigenic determinants also occurred less frequently as adw+yr-, adwr+y-, and awr+dy-. These unusual samples which contain both w and r may be the result of mixed particles, recombination of virus, mixing of viral proteins in doubly infected cells or extracellular aggregation of mixed viral products.