Seroprevalence of bactericidal antibodies against serogroup B and C Meningococci in a University Hospital.

Meningococcus serogroup B (MenB), clonal complex 32 (cc 32), was the Brazilian epidemic strain of meningococcal disease (MD) in the 1990's. Currently, meningococcus serogroup C (MenC), cc 103, is responsible for most of the cases of the disease in Brazil. The aim of this study was to investigate the seroprevalence of bactericidal antibody (SBA) against representative epidemic strains of MenC, (N753/00 strain, C:23:P1.22,14-6, cc103) and MenB, (Cu385/83 strain, B:4,7:P1.15,19, cc32) in students and employees of a university hospital in the State of Rio Grande do Sul (RS, Brazil). A second MenC strain (N79/96, C:2b:P1.5-2,10, cc 8) was used as a prototype strain of Rio de Janeiro's outbreak that occurred in the 1990's. Our previous study showed a 9% rate of asymptomatic carriers in these same individuals. A second goal was to compare the SBA prevalence in meningococcal carriers and non-carriers. Fifty-nine percent of the studied population showed protective levels of SBA titers (log2≥2) against at least one of the three strains. About 40% of the individuals had protective levels of SBA against N753/00 and Cu385/83 strains. Nonetheless, only 22% of the individuals showed protective levels against N79/96 strain. Significantly higher antibody levels were seen in carriers compared to non-carriers (P≤0.009). This study showed that, similar to other States in Brazil, a MenC (23:P1.22,14-6, cc103) strain with epidemic potential is circulating in this hospital. Close control by the Epidemiological Surveillance Agency of RS of the number of cases of MD caused by MenC strains in the State is recommended to prevent a new disease outbreak.

Differential capacities of outer membrane proteins from Neisseria meningitidis B to prime the murine immune system after vaccination.

Understanding the specificity of antibody response to Neisseria meningitidis serogroup B (Men B) is a key requirement for the development of an effective vaccine. This study was designed to investigate the antigen specificity of murine IgG1 and IgG2b antibodies induced by different primary immunization schedules and the booster dose with the Cuban Men B vaccine. Immunoblotting analyses were performed using outer membrane vesicles (OMV) from the vaccine strain (B:4,7:P1.19,15). IgG subclasses binding to PorA, PorB and RmpM were determined by digital scanning of the immunoreactive bands. Bactericidal antibody response after vaccination was also evaluated. The results indicated that IgG2b anti-PorA was the main antibody response induced by two doses of the vaccine. A primary series of three doses was found important for increasing IgG2b as well as IgG1 to PorB and RmpM. The fourth dose favoured the recognition of RmpM as detected by the increase of specific IgG1 and IgG2b. IgG subclasses anti-PorA did not change significantly if animals received two, three or four doses of the vaccine during the primary immunization or after the booster dose for all vaccine groups. The booster response to PorB and RmpM of groups BC2 and BC3 showed a significant increase in IgG2b levels compared with the primary response. However, the recall and the primary response of group BC4 were similar, suggesting a saturated dose-effect response after four doses of vaccine. The same was seen for bactericidal antibody response when human complement source was used in the assay.