The PorX/PorY-determined virulence of P. gingivalis W83 strains.A, virulence assay of P. gingivalis W83 wild-type, ΔporX (YS19145), and ΔporY (YS19153) strains. Groups of mice (n = 5) were inoculated with an indicated dose of P. gingivalis cells. B, LD50 of P. gingivalis W83. Groups of mice (n = 5) were inoculated with indicated doses of P. gingivalis cells. C, virulence assay of P. gingivalis W83 wild-type and ΔporX strains grown at different times. Groups of mice (n = 5) were inoculated with 2 to 4 × 109 CFU of P. gingivalis cells.