Reduction of Adherence Ability of Porphyromonas gingivalis to Epithelial Cells by Loss of Fimbriae

The adherence to human buccal epithelial cells was compared between non-fimbriated and fimbriated strains of Porphyromonas gingivalis. The non-fimbriated strain was isolated from P. gingivalis 381 fimbriated strain by culturing the bacteria with the monoclonal antibody which was specific against the fimbriae of strain 381. The non-fimbriated strain did not agglutinate with the monoclonal antibody or anti-fimbriae antiserum, while it agglutinated with antiserum to whole P. gingivalis 381 cells. Fimbriae were not detected on the surface of non-fimbriated strain by electron microscopy. The adherence of the non-fimbriated strain to epithelial cells was significantly reduced in comparison to that of the original fimbriated strain 381. The mean number of bacteria adhering to epithelial cells was only 9.0± 12.0/buccal cell in the non-fimbriated strain and 92.9•}38.7 in the original strain 381. The hemagglutinating ability was not affected by loss of fimbriae. Additionally, fimbriae did not show hemagglutinating activity. The results indicated that the fimbriae of P. gingivalis 381 are largely responsible for the bacterial adherence to epithelial cells but were not essential for hemagglutinating ability