Interactions of gonococci with HeLa cells: attachment, detachment, replication, penetration, and the role of protein...

Colony variants of Neisseria gonorrhoeae differ in their interactions with eucaryotic cells. When gonococci were cultivated with HeLa cell monolayers, the opacity phenotype (Op) became increasingly dominant in the subpopulation of organisms which adhered to the HeLa cells. Once bound, Op organisms displayed very low levels of detachment. Adherent Op gonococci exhibited generation times up to threefold greater than cultures containing gonococci in the absence of HeLa cells. In addition, the progeny of adherent Op organisms remained bound to the HeLa cell monolayer. Both piliated (P+) and transparent (Tr) colony types attached to HeLa cells, but their progeny were retained less efficiently. Gonococci bound to HeLa cells were subjected to the bactericidal action of fresh rat serum and approximately 0.5 to 2.5% survived, irrespective of their opacity or piliation phenotype. Incubation with gentamicin resulted in a 10- to 50-fold further reduction in viability. Pretreatment of HeLa cell monolayers with the microfilament-disrupting agent cytochalasin b diminished gonococcal survival in either serum or gentamicin by up to eightfold. In contrast, cytochalasin b treatment did not decrease survival of the commensal organism N. sicca. The data suggest that very few gonococci are completely interiorized and a small proportion of adherent gonococci are partially protected from the soluble-phase environment by HeLa cells.