Immunological and biochemical studies of meningococcal C polysaccharides isolated by diethylaminoethyl chromatography.

Meningococcal C polysaccharides isolated from the broth supernatant of C1+ and C1- strains by a combination of Sepharose 4B and diethylaminoethyl-52 chromatography are antigenically identical to the group C antigen isolated by the Cetavlon procedure. Immunizations result in the induction of precipitating, hemagglutinating, and bactericidal antibodies in rabbits and sheep and hemagglutinating and bactericidal antibodies in rabbits and sheep and hemagglutinating and bactericidal antibodies in gerbils. Selective destruction of C1- polysaccharides with neuraminidase has demonstrated that these antibodies are directed against the C polysaccharide. Neuraminidase digestions of the C1- polysaccharides resulted in release of up to 84% of the antigen as N-acetylneuraminic acid. C1+ polysaccharides proved to be more resistant to neuraminidase, requiring greater concentrations of enzyme and longer intervals of exposure for digestion. Chemical analysis of the C1+ and C1- polysaccharides indicated that they contain less than 0.5% protein and less than 0.5% nucleic acid.