ANTIGENIC, STRUCTURAL, AND FUNCTIONAL-RELATIONSHIPS BETWEEN FIMBRIAE AND THE HEMAGGLUTINATING ADHESIN HA-AG2 OF PORPHYROMONAS-GINGIVALIS

While the adhesive properties of Porphyromonas gingivalis are known to allow colonization of the subgingival tissues, the roles of fimbriae and adhesin molecules in hemagglutination remain unclear, The purpose of this study was to analyze the antigenic, structural, and functional relationships of these two components, Five populations of monoclonal antibodies were produced against (i) the hemagglutinating adhesin HA- Ag2 resolved by crossed immunoelectrophoresis (CIE), (ii) native fimbr iae, and (iii) each of the three immunoprecipitates, Ag8a, Ag8b, and A g8c, that define fimbriae by CIE, The tests used for characterization of the monoclonal antibodies included immunoblot reactivity, inhibitio n of hemagglutination, capacity to dissociate immunoprecipitates by CI E, localization of recognized epitopes by immunoelectron microscopy, a nd epitope mapping by competition enzyme linked immunosorbent assay, T he results from the different immunochemical tests clearly showed a cl ose antigenic relationship between fimbriae and the hemagglutinating a dhesin HA-Ag2. We were able to establish that the epitopic domain H-1 of HA-Ag2 is hemagglutinin specific and that domain F-2 is fimbria spe cific, Our data indicate that the polymeric structural unit of fimbria e must be complexed to HA-Ag2, the adhesin, to confer hemagglutination activity to the bacterial cells.