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 of 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 summit 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. 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.