Serotype determinant protein of Neisseria Meningitidis. Large scale preparation by direct detergent treatment of the bacterial cells.

Neisseria meningitidis Group B microorganisms, inactivated with phenol and harvested by centrifugation, were subjected to direct treatment with various detergents to solubilize the serotype determinant proteins localized in the outer membrane. Analysis of the data showed that extraction of the cells with detergents provided yields of the serotype protein substantially exceeding those obtained by simple salt extraction of the bacteria. Routinely, more than 2 mg of end product per g of cell mass (wet weight) may be recovered by the present method. By gel chromatographic analysis, the serotype determinant protein was shown to interact with the capsular polysaccharides derived from Group A or C Neisseria meningitidis microorganisms, forming high molecular weight complexes. This interaction markedly enhanced the solubility of the serotype determinant protein. Combined vaccines of the type-specific protein with the group- specific polysaccharides were evaluated for their immunogenic potential in the subcutaneous steel spring implant model. In guinea pigs, amounts corresponding to 10 micrograms completely prevented infection upon challenge with homologous organisms four weeks after immunization. Partial protection was observed with immunizing doses corresponding to 2 micrograms or 0.4 micrograms/animal, respectively. Compared to lyophilized preparations, vaccines adsorbed to a mineral carrier were slightly less effective in inducing protection, whereas inclusion of Bordetella pertussis as a component of the vaccine stimulated the immune response.