Distribution and immunochemical specificities of fimbriae of Porphyromonas gingivalis and related bacterial species.

Rabbit polyclonal antibody (Poly-1) and mouse monoclonal antibodies (mAbs) TO-11, TO-14 and TO-M1 specific for Porphyromonas gingivalis 381 fimbriae were prepared. Poly-1 and the 3 mAbs were screened for their reactivity with whole cells oral and nonoral black-pigmented bacterial species by enzyme-linked immunosorbent assay (ELISA) and the binding experiment using [125I]Poly-1 and [125I]mAbs. ELISA revealed that Poly-1 definitely reacted with whole cells of all the 11 strains of P. gingivalis tested. However, 8 of 11 P. gingivalis strains reacted with mAbs TO-11, TO-14 and TO-M1. These results were confirmed by the specific binding of radiolabelled Poly-1 and mAb TO-11 to the 8 strains. The M(r) of the fimbrial subunit protein (fimbrilin) isolated and purified from P. gingivalis strains 381, BH18/10, HW24D-1, 6/26 and OMZ 314 was 41 kDa by sodium dodecylsulfate-polyacrylamide gel electrophoresis. It was found by immunoblotting that mAbs TO-11 and TO-14/TO-M1 recognized different epitopes of fimbrial protein from P. gingivalis strains. Immunoelectron micrographs of whole cells and the purified fimbriae of P. gingivalis strains visualized similar serotype-specific antibody bindings to the fimbriae. These results indicate that 11 strains of P. gingivalis could be divided into at least 2 separate groups based on the immunochemical specificities of the fimbriae.