Human antibody and memory B and T-cell responses after primary and booster immunisation against Neisseria meningitidis B.

Vaccination against disease aims at the induction of long-lasting cellular and humoral immune responses. Few studies have addressed the mechanisms by which meningococcal vaccines generate and sustain immunological memory. The goal of this study was to investigate the development of long-term humoral and cellular memory to Neisseria meningitidis serogroup B (MenB) in health subjects after immunisation with the Cuban outer membrane protein (OMP) vaccine (VA-MENGOC-BC). The results showed that three doses of vaccine were necessary to induce a detectable memory B-cell response (mean of 0.46%) which became undetectable 6 months later. After boosting, only 2 of 5 individuals responded with an increase in memory B-cell frequencies (values of 0.15% and 0.34%). Bactericidal and opsonic antibody levels were higher after primary immunisation (log(2) mean and median of 4.7 and 1212, respectively) when compared with post-booster response (log(2) mean of 2.6 and median of 285, respectively). Together, these data suggest a failure of vaccine to induce long-term memory B-cell and serological memory in adults. However, we observed a significant and functional memory T-cell response specially after boosting, with a predominance of activated (CD69(+)) central memory T-cell (CD4(+)CD45(-)CCR7(+)) response. Therefore, this study suggests that vaccination with the MenB vaccine induced the generation and activation of memory T-cells but failed to maintain the memory B-cell population at a stable size and/or function.