A ROLE FOR FIMBRIAE IN PORPHYROMONAS-GINGIVALIS INVASION OF ORAL EPITHELIAL-CELLS

Isogenic mutants of Porphyromonas gingivalis which differ in the expre ssion of fimbriae were used to examine the contribution of fimbriae in invasion of a human oral epithelial cell line (KB). At a multiplicity of infection of 100, the wild-type P. gingivalis strains 33277, 381, and A7436 exhibited adherence efficiencies of 5.5, 0.11, and 5.0% resp ectively, and invasion efficiencies of 0.15, 0.03, and 0.10%, respecti vely. However, adherence to and invasion of KB cells was not detected with the P. gingivalis fumA mutants, DPG3 and MPG1. Adherence of P. gi ngivalis wild-type strains to ICE cells was completely inhibited by th e addition of hyperimmune sera raised to the major fimbriae. Examinati on by electron microscopy of invasion of epithelial cells by the P. gi ngivalis wild-type strain 381 reveled microvillus-like extensions arou nd adherent bacteria; this was not observed with P. gingivalis fum mut ants. Taken together, these results indicate that the P. gingivalis ma jor fimbriae are required for adherence to and invasion of oral epithe lial cells.