Cross-reactions between Neisseria meningitidis and twenty-seven other bacterial species.

Cross-reactions between antigens from N. meningitidis and antigens from 27 other bacterial species from clinical isolates representing 20 different genera were studied by quantitative immunoelectrophoretic methods. A water-soluble N. meningitidis antigen preparation and a corresponding pooled rabbit antiserum regularly presenting 48 immunoprecipitates were used as reference system. Antigens from 16 other bacterial genera cross-reacted with one to four N. meningitidis antigens, whereas antigens from six other Neisseria species cross-reacted with 37 to 48 N. meningitidis antigens. Antigens from only three bacterial genera (Streptococcus, Staphylococcus and Bacteroides) did not show any cross-reactions. The degree of cross-reactivity between the antigens were 25--100%, as judged by absorption of antibodies. Three of the cross-reacting antigens reacted with normally occurring precipitating antibodies in serum from humans and rabbits.