[A common meningococcaL intergroup antigen: immunological and immunochemical study].

Protein-containing preparations forming 1 precipitation line in highly sensitive immunoelectrophoretic tests have been obtained from the culture fluid of meningococci, groups A, C and X. The preparations have been found to render a very high degree of protection to mice challenged with meningococci of the homologous serogroup and a sufficiently high degree of protection to those challenged with meningococci of the heterologous serogroups. After the repeated injection of the preparations the appearance of the booster effect has been registered. Immunochemical study has shown that the preparation is a stable complex consisting of protein, group-specific polysaccharide and a heat-resistant component common for serogroups A, C, X and Y.