Immunological and serological diversity of Neisseria gonorrhoeae: gonococcal serotypes and their relationship with immunotypes.

Strains of gonococcus were shown to be immunologically heterologous. Serum bactericidal activity generally correlated with induced immunity to gonococcal challenge as detected by the guinea pig subcutaneous chamber model. Sera devoid of bactericidal activity reflected the lack of cross-protection in subcutaneous chambers. Factors affecting the bactericidal assay described in this report include (i) source of complement, (ii) concentration of test antigen and complement activity, and (iii) presence of calcium and magnesium ions and bovine serum albumin in diluent. Poor correlation was observed between agglutinating activity of the immune sera and protection.