Generation of long-lived plasma cells to serogroup B Neisseria meningitidis after murine immunisation with an outer membrane protein vaccine.

There is no universal vaccine against serogroup B meningococcus (Men B). We investigated the development of spleen and bone marrow-specific IgG-secreting plasma cells (ASC) in mice immunised with the Cuban outer membrane protein (OMP) vaccine (VA-MENGOC-BC). Bone marrow was the predominant anatomical site of specific ASC and showed constant ASC levels (approximately 4%) at each time point analysed, indicating the production of long-lived ASC. A mean of 2.36 and 0.35% of Men B ASC was detected in spleen after the third dose and 2 months later, respectively, indicating a short-lived population. The data suggest that a short-lived ASC population in spleen was responsible for serum IgG anti-OMP while ASC from bone marrow produced persistent bactericidal antibodies against the vaccine strain. The response to the booster dose was consistent with development of memory B cells by primary vaccination.

Effect of a booster dose of serogroup B meningococcal vaccine on antibody response to Neisseria meningitidis in mice vaccinated with different immunization schedules.

The generation and maintenance of memory antibody response by different primary immunization schedules with the Cuban-produced outer membrane protein based vaccine was investigated in a murine model. We analyzed the duration of the antibody response (IgG-ELISA and bactericidal titer) and the effect of a booster dose on the antibody response. The IgG avidity index was determined in an attempt to find a marker for memory development. This study also included an analysis of IgG subclasses induced by primary and booster immunization. The specificity of bactericidal antibodies was investigated using local strains of the same serotype/serosubtype (4,7:P1.19,15) as the vaccine strain and mutant strains lacking major outer membrane proteins. A significant recall response was induced by a booster dose given 7 months after a primary series of 2, 3 or 4 doses of vaccine. The primary antibody response showed a positive dose-effect. In contrast, a negative dose-effect was found on the booster bactericidal antibody response. There was a significant increase in IgG1 levels after the fourth and booster doses. Three doses of vaccine were required to induce a significant increase in IgG avidity. Two injections of vaccine induced a significant antibody response to PorA protein, while 4 injections induced a larger range of specificities.