A series of seven antigenically distinct polysaccharides have been isolated from the lipopolysaccharide of Group B meningococci. Using these antigens as a basis, the objectives of this proposal are: 1) the elucidation of the antigenic structure of the LPS-derived polysaccharides from pathogenic meningococci (serogroups A, B, C, X and Y) with the goal of developing a comprehensive LPS based serotyping system for these meningococci. A corollary to this objective would include a search for antigenic determinants on the LPS-polysaccharide which are common to these meningococci; 2) the physicochemical analysis of the serotype polysaccharides. In addition to physical and chemical investigations, these studies would include methods to conjugate these polysaccharides to other biological materials in an attempt to modify the polysaccharide structures chemically to produce immunogens with low toxicity and improved immunogenicity. 3) to study the immunogenicity and protective value of these polysaccharides, both as the purified polysaccharides and as the purified polysaccharides conjugated to other biologic materials. These antigens will be isolated from meningococcal phenol water endotoxin by DEAE chromatography after alkaline hydrolysis. Rabbit immunizations will be performed with whole organisms and antisera to isolated antigens will be produced in hybridoma systems. Sero-typing systems will be developed using co-agglutination. Immunoprotection ability of the various antigens will be tested in the mouse-Imferon model.