Abstract

Porphyromonas gingivalis (P. gingivalis) fimbriae are classified into six types (Types I to V and Ib) based on the fimA genes encoding FimA (a subunit of fimbriae), and they play a critical role in bacterial adhesion to and invasion of gingival epithelium. Accumulated evidences suggest that P. gingivalis strains with Type II fimbriae (designated Pg-II) are more virulent than other types. This study aimed to compare the abilities in adhesion to and invasion of oral epithelial cells of Pg-II strains. P. gingivalis strains were isolated from Chinese patients with chronic periodontitis using conventional anaerobic separation techniques. Adherent and invasive properties of P. gingivalis were measured by standard methods, and confirmed by both scanning and transmission electron microscopy.Analysis of eight Pg-II strains showed significant differences in their adherent and invasive capabilities, but there was no significant correlation between the fimA genotype and the adhesion and invasion abilities of the bacteria. The results suggest that adherent and invasive heterogeneities exist among Pg-II strains and that there must be other factors that influence the virulence of P. gingivalis with distinct fimA genotypes.

Key words: P. gingivalis, fimbriae, fimA genotype, adhesion, invasion.