Antibody studies in mice of outer membrane antigens for use in an improved meningococcal B and C vaccine

Since 1988, N. meningitis, B:4:P1.15, ET-5 complex, has been responsible for an epidemic of meningococcal disease in Greater Sao Paulo, Brazil. Despite current trials to develop an effective vaccine against group B meningococci, children less than 2 years old have not been protected. It has been suggested that iron-regulated proteins (IRPs) should be considered as potential antigens for meningococcal vaccines. The vaccines under study consisted of outer-membrane vesicles depleted of lipooligosaccharide from three serogroup B strains and one serogroup C strain, IRPs, meningococcal group C polysaccharide and aluminum hydroxide. Four different protein and C: polysaccharide concentrations were studied. The ELISA and bactericidal results showed a higher antibody response when 2 injections of 2.0 mu g doses were administered. Despite higher IgG reactivity against antigen preparations-containing IRPs seen in ELISA, the bactericidal activity was not increased if the target strain was grown in iron-restricted medium, The influence of addition of alkaline-detoxified lipooligosaccharide (dLOS) on immunogenicity of the vaccine was also investigated, and the dLOS provided for a functionally specific antibody response.