The Role of Common and Type-specific Pilus Antigenic Domains in Adhesion and Virulence of Gonococci for Human Epithelial Cells

A panel of monoclonal antibodies with varying pilus specificities ranging from cross-reacting to type-specific has been used to investigate the role of conserved and variable antigenic domains in the adhesion of gonococci to human epithelial cells. The binding of 125I-labelled alpha pili from strain P9 to buccal epithelial cells was inhibited by three type-specific but not by two cross-reacting antibodies. Four type-specific antibodies inhibited the binding of gamma pili while the two cross-reacting antibodies were again without effect. The virulence of the variants P9-2 (alpha pili) and P9-35 (gamma pili) for Chang conjunctiva epithelial cells was similarly reduced only in the presence of relevant type-specific antibodies. These results indicate the importance of variable antigenic domains in the adhesion of gonococci to human epithelial cells.