Analysis of the ontogeny of the murine humoral response to Neisseria meningitidis B capsular polysaccharide reveals levels of complexity relevant to vaccine development

Although purified capsular polysaccharide of Neisseria meningitidis group B (CpsB) is not immunogenic at any age, CpsB on the bacterial surface elicit s antibody responses late in ontogeny. Therefore, a detailed analysis of th e ontogeny of the murine anti-CpsB response to N. meningitidis could determ ine key parameters regarding the poor immunogenicity of CpsB. The effects o f bacterial dose, hyperimmunization, age, and sex on the induction of prima ry and secondary anti-CpsB immunoglobulin isotype profiles were studied. It was demonstrated that the timing and repetition of immunization and of the bacterial dose have a marked differential effect on the primary induction of anti-CpsB immunoglobulin isotypes and on the ability to induce anti-CpsB antibody responses after subsequent rechallenge. It is noteworthy that the ontogeny of the response is related to the appearance of natural anti-CpsB antibodies, but this is not associated with the presence of CpsB cross-rea ctive antigens in the microflora.