Monoclonal radioimmunoassays for hepatitis B surface antigen: demonstration of hepatitis B virus DNA or related sequences in serum and viral epitopes in immune complexes.

High-affinity monoclonal IgM and IgG antibodies (anti-HBs) to hepatitis B surface antigen (HBsAg) have recently been developed and used by us in the construction of highly sensitive radioimmunoassays for the detection of HBsAg-associated determinants in serum. We now report that selected serum samples demonstrating monoclonal immunoreactive material also contain nucleic acid sequences complementary to hepatitis B virus (HBV) DNA by molecular hybridization analysis. In addition, monoclonal radioimmunoassays can detect viral determinants in HBsAg-anti-HBs immune complexes formed in anti-HBs excess; such determinants are undetectable by commercial radioimmunoassay. These and our previous studies suggest that there are HBV or "HBV-related" agents present in human serum that are detected by monoclonal antibodies but are not identified by conventional polyvalent antibodies.