Deficiency of complement proteins C5 to C8 leads to increased infection by which of the following?

The terminal components of complement C5, 6, 7, 8, and 9 are required for the assembly of the membrane attack complex involved in the lysis of organisms. The deposition of the membrane attack complex on cells makes these cells permeable to water and ions and results in osmotic lysis of the cells. This role of complement is paicularly impoant for killing microbes with thin cell walls, such as Neisseria bacteria, and deficiency of the terminal components of complement (except C9) predisposes to Neisseria infections (gonococcal and meningococcal).