Immunological characteristics of gonococcal outer membrane protein II assessed by immunoprecipitation, immunoblotting, and coagglutination

Immunoprecipitation or coagglutination with whole gonococci and immunoblotting have been used to assess the comparative antigenicities of 11 different protein II (P.II) moieties from four different strains. Rabbit antisera used for these studies include both anti-whole gonococcal sera and antisera raised by immunization with "isolated" P.II preparations. The results show that: (a) immunization with gonococci possessing a single P.II elicits formation of antibodies directed mainly at the homologous P.II when assessed by either immunoprecipitation or immunoblotting; and (b) immunization with isolated P.II material elicits formation of antibodies that are cross-reactive with all (or nearly all) P.II species in immunoblots; these antibodies recognize mainly the homologous P.II by immunoprecipitation. These results have been interpreted as showing the following: (a) all gonococcal outer membrane P.II moieties share antigenic determiners, but these common antigens are not generally accessible on the organisms' surfaces for interaction with antibody molecules; and (b) the surface-exposed antigens of different P.II constituents are, in general, different from one another.