Complement interactions with the pathogenic Neisseriae: clinical features, deficiency states and evasion mechanisms

Neisseria gonorrhoeaecauses the sexually transmitted infection gonorrhea, whileNeisseria meningitidisis an important cause of bacterial meningitis and sepsis. Complement is a central arm of innate immune defenses and plays an important role in combating Neisserial infections. Persons with congenital and acquired defects in complement are at a significantly higher risk for invasive Neisserial infections such as invasive meningococcal disease and disseminated gonococcal infection compared to the general population. Of note,Neisseria gonorrhoeaeandNeisseria meningitidiscan only infect humans, which in part may be related to their ability to evade only human complement. This review summarizes the epidemiologic and clinical aspects of Neisserial infections in persons with defects in the complement system. Mechanisms used by these pathogens to subvert killing by complement and preclinical studies showing how these complement evasion strategies may be used to counteract the global threat of meningococcal and gonococcal infections are discussed.