Meningococcal (Neisseria meningitidis) infection is predisposed by deficiency of -

Ans. is 'a' i.e., Late complement Complement deficiency and neisserial infections* The complement system is an essential component of the innate immune defence against infection by Neisseria (N. Meningitidis and N. gonorrhoeae).* People who lack or have a deficiency in complement mediated bactericidal activity are most susceptible to neisserial diseases.* Terminal complement component (C5 through C9) deficiencies and deficiencies of the alternative pathway (Properdin, C3' Factor D) have a strong effect on susceptibility to, as well as severity of, neisserial infections.1) Deficiency of terminal complement (C5 - C9) componentDeficiency of one of the terminal components that compose membrane attack complex (MAC) predisposes patients to infection with Neisseria meningitides or Neisseria gonorrhoeae. However, N. meningitidis infection is more common.2) Deficiencies of terminal pathway Deficiencies in components of alternative pathway, namely properdin, C3 and factor D, have been associated with increased susceptibility, almost exclusively, to meningococcal infection (amongst Neisseria).