Monoclonal antibodies to gonococcal pili: studies on antigenic determinants on pili from variants of strain P9.

Several hybrid cell lines producing monoclonal antibodies against gonococcal pili have been derived. The reactivity of each antibody against variant pili of strain P9 was determined by ELISA. Using type-specific as well as broadly cross-reacting antibodies labelled with 125I, the capacity of unlabelled hybridoma antibodies to inhibit their attachment to various pilus types was determined. Some antibodies competed significantly and were judged to react at the same or closely positioned antigenic sites, whereas others bound non-competitively to the same pilus. These studies suggest the existence of distinct antigenic sites on gonococcal pili: a common antigenic region shared by all P9 pilus types and a type-specific region. Both antigenic sites contain more than one epitope.