Bacterial Entry and Intracellular Processing of Neisseria gonorrhoeae in Epithelial Cells : Immunomorphological Evidence for Alterations in the Major Outer Membrane Protein RIB By Jan

The fate of the major outer membrane protein of the gonococcus, RIB, during the adherence, entry, and intracellular processing ofthe bacteria in infected epithelial cells was investigated using post-embedding immunoelectron microscopy. Various domains ofthe RIB molecule were probed at different stages in the infection. These studies revealed that RIB epitope exposure remained unaltered during the initial attachment ofthe bacteria to the host cells . In contrast, upon secondary attachment of the bacteria to the eukaryotic cells, apparent zones of adhesion were formed between the gonococci and the host cell membrane, which were characterized by loss of a defined RIB epitope . These zones of adhesion with the altered RIB immunoreactivity continued to exist and increased in number during cellular penetration, suggesting that they were essential to bacterial invasion into the eukaryotic cells. After bacterial entry, two classes ofgonococci could be recognized; morphologically intact, RIB-positive bacteria and disintegrated organisms that showed a change in, and, in a later stage, a complete loss of RIB immunoreactivity. The intracellular alterations in the RIB antigen could be prevented by treatment of the host cells with the lysosomotropic agent chloroquine. These observations point to a mechanism by which a subpopulation of intracellular gonococci can escape the epithelial cell defense by preventing or resisting exposure to host cell proteolytic activity.