Structural relationships between hepatitis B surface antigen in human plasma and dimers from recombinant vaccine: a...

Ten monoclonal antibodies were obtained from mice immunized with a yeast recombinant hepatitis B vaccine. They were selected at an early stage for their ability to bind to native surface antigen particles (HBsAg) in human plasma. All antibodies recognized conformational epitopes which were destroyed completely or almost completely by reduction of disulphide bridges. They were divided into five epitope groups by their competition for binding to recombinant S protein, though epitopes within each group are not identical. Recombinant S protein migrated on SDS-PAGE in the absence of reducing agents as a mixture of monomers and dimers/oligomers. Sucrose gradient analysis suggests that all these forms are co-aggregated into HBsAg-like particles. On Western blots, all ten antibodies either bound only to dimers/oligomers or strongly preferred them over monomers. The results suggest that, of the antibodies produced in response to recombinant vaccine in mice, most of those which bind strongly to 'native' HBsAg particles in human plasma recognize surface structures created by interaction between two subunits.