Role Of Acquired Immunity In Neisseria Infections

A description of the clinical features of meningococcal disease first appears in the literature in 1805 in a thesis on an outbreak in Geneva, yet the global distribution of the organism and the diversity of its surface structures indicate a far longer history of association with man (perhaps as an acapsulate commensal), with diversity likely driven by immune-selection. Carriage studies indicate that almost all humans are likely to be exposed to Neisseria meningitidis at some stage and yet most do not develop disease. In early childhood, after loss of maternal antibody and before acquisition of adaptive immunity, the innate immune system effectively controls the meningococcus in most exposed individuals and prevents onset of invasive disease. However, the lower rates of disease in later childhood and amongst adults who have acquired specific antibody to the meningococcal surface indicates that the adaptive immune system is better still at preventing invasion into the bloodstream. In the first portion of this chapter we will consider both the natural acquisition of adaptive immunity to the meningococcus and the active induction of specific antibody through immunization. There will also be a discussion regarding gonococcal acquired immunity at the end of this chapter.