The phase-variable pilus-associated protein PilC is commonly expressed in clinical isolates of Neisseria gonorrhoeae, and shows sequence variability among strains.

PilC is a phase-variable protein associated with pilus-mediated adherence of pathogenic Neisseria to target cells. In this study, 24 strains of Neisseria gonorrhoeae with known epidemiological data were examined for expression of PilC. All strains produced PilC independently of serovar and site of isolation. To investigate whether the PilC protein is conserved or variable among gonococcal strains, the complete nucleotide sequence of pilC in four strains, isolated from either rectum, throat or blood, was determined. The deduced amino acid sequence in these strains differed from each other and from the two PilC proteins of N. gonorrhoeae MS11. These data demonstrate that PilC is commonly expressed, but the PilC sequence may vary among gonococcal strains.