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As revealed in animal experiments, the formation of antibodies to group-B N. meningitidis antigens (group-specific polysaccharide, lipopolysaccharide and outer membrane proteins) in response to administration of meningococcal corpuscular preparations depends on the method of administration, the dose, and the number of administrations. In the sera of rabbits, immunized orally, antibodies to all three antigens in sufficiently high titers have been detected.

Group B meningococcal vaccine consisting of the natural complex of specific polysaccharide and outer membrane protein (OMP) has been shown to be moderately reactogenic, safe with respect to the effect of undermining tolerance to human brain tissue antigens and to produce no allergization of humans. The vaccine under study possesses antigenic activity: (a) immunization with this vaccine ensures the fourfold rise of the level of antibodies to the group-specific polysaccharide of group B meningococcus in about 80% of persons with the initially low level of antibodies, this percentage being retained during the whole period of observation, i. e. 85 days; (b) the vaccine enhances the level of antibodies to meningococcal OMP, determined in the enzyme immunoassay and the passive hemagglutination test; (c) these data are indicative of the expediency of immunizing the risk groups of persons with the initially low level of antibodies.

The protein-polysaccharide complex, isolated from group B N. meningitidis, is a variant of vaccine for the prophylaxis of group B N. meningitidis infection. In this investigation the influence of the complex of the physical properties of aluminium hydroxide gels, the amount of gel, pH and the duration of sorption on the process of sorption has been studied. Aluminium hydroxide has been shown to produce a stimulating effect on the response of mice to the polysaccharide and protein contained in the complex after immunization made in two injections. Gels with a smaller particle size have been found to possess greater adjuvant activity, as well as greater absorbing activity. The immunological activity of the complex, adsorbed ex tempore, has proved to be no different from that of the complex adsorbed in an hour.

The continuous synchronous cultivation of serogroup B meningococci and the use of the selected clones of producer strains has made it possible to obtain the serologically active preparation of the group-specific antigen from the culture in the exponential phase. The erythrocyte diagnosticum produced on the basis of this preparation has permitted the detection of group-specific antibodies in the sera of immunized rabbits and children with generalized infection caused by serogroup B meningococci. The intensity of immune response depends on the age of children. This new technique of the passive hemagglutination test is recommended for the confirmation of generalized infection caused by serogroup B meningococci.

Both surface and intracytoplasmic vesiculae have been shown to appear in meningococcal cells, strains 132, 125, and 133 belonging, respectively, to serogroups A, B, and C, in the process of batch cultivation. The surface microvesiculae are formed from the outer membrane of the cell wall during the whole process of batch cultivation. The intracytoplasmic membrane structures are formed in the process of cell autolysis. As revealed in this investigation, the strains under study, irrespective of their serogroup, are characterized by similar mechanisms of the formation of microvesiculae. The surface microvesiculae have been found to fall into three main types: monolamellar, multilamellar, and large spheroid bodies. The presence of specific functional features in each type of surface microvesiculae is suggested, as these microvesiculae, besides having their characteristic ultrastructure, differ in their contents. The attenuated culture of meningococcal strain 133, whose cells are notable among other strains under study for their more active (quantitatively) formation of microvesiculae, has been shown to have the highest toxicity for rabbits.