Fate of the major outer membrane protein P.IA in early and late events of gonococcal infection of epithelial cells.

We investigated the fate of the major outer membrane protein of Neisseria gonorrhoeae, P.IA, during gonococcal infection of Chang conjunctiva epithelial cells by using immunoelectron microscopy. Probing of P.IA epitopes with mono- and polyclonal antibodies revealed variable, fixation-dependent P.IA epitope exposure in the gonococci used as an inoculum in the infection experiments. Detection of invariable exposed P.IA epitopes in cryosections of infected epithelial cells with a polyclonal antiserum revealed unaltered P.IA exposure on the bacterial membranes during early attachment of the bacteria to the eukaryotic cells. Upon entry of the bacteria into the host cells, however, labelling was extended to membraneous structures that intercalated between the bacteria and the host cell surface, and, occasionally, to the host cell plasma membrane. The latter observation is consistent with the suggested active role of P.I. in the uptake process (as shown in 1985 by E.C. Gotschlich). Once inside the epithelial cells, both morphologically intact and disintegrating bacteria could be distinguished. The disintegration of the bacteria was accompanied by a loss of P.IA immunoreactivity.