Immunoprecipitation Analysis of Soluble Complement-Fixing Antigens of Dengue Viruses

Abstract

Abstract Soluble complement-fixing antigens were obtained from brains of suckling mice infected with each of the four dengue serotypes. Brain suspensions were partially purified by clarification with protamine sulfate, precipitation of the antigen with ammonium sulfate, and gel filtration on Sephadex G-100. Antigenic relationships of the partially purified antigens were examined by complement-fixation and Ouchterlony type immunoprecipitation. Discrete precipitin lines were formed with soluble complement-fixing antigens and hyperimmune mouse ascitic fluid. An antigenic determinant common to all four dengue serotypes was demonstrated by both complement-fixation and immunoprecipitation. Cross-absorption experiments confirmed the presence of the group antigen. Spur formation indicated the presence of a unique type-specific antigen for each serotype. Immunoprecipitation patterns indicated that both group- and type-specific antigenic determinants were on the same molecule and that separate antibodies were formed to each determinant.