Immunogenicity and bactericidal activity in mice of an outer membrane protein vesicle vaccine against Neisseria meningitidis serogroup A disease.

Serogroup A Neisseria meningitidis organisms of the subgroup III have caused epidemics of meningitis in sub-Saharan Africa since their introduction into the continent in 1987. The population structure of these bacteria is basically clonal, and these meningococci are strikingly similar in their major outer membrane antigens PorA and PorB. Protein-based vaccines might be an alternative to prevent epidemics caused by these meningococci; thus, we developed an outer membrane vesicle (OMV) vaccine from a serogroup A meningococcal strain of subgroup III. The serogroup A OMV vaccine was highly immunogenic in mice and elicited significant bactericidal activity towards several other serogroup A meningococci of subgroup III. The IgG antibodies generated were in immunoblot shown to be mainly directed towards the PorA outer membrane protein. The results presented demonstrate the potential of an OMV vaccine as an optional strategy to protect against meningococcal disease caused by serogroup A in Africa.