FIG. 6.

The virB9 mutant Cfv 3-18 shows an impaired cytotoxic phenotype in continuous coculture with HeLa cells. HeLa cells were grown to confluence and then infected in triplicate at an MOI of 100 with either C. fetus subsp. venerealis ATCC 19438 (CfvT) or Cfv 3-18. (A) The number of surviving HeLa cells relative to uninfected control cultures is indicated. (B) The number of viable bacteria in the cell culture medium was determined daily. No statistical difference between CfvT and Cfv 3-18 was observed. The values shown are averages of 3 independent experiments. Statistical significance is indicated: *, P < 0.05; **, P < 0.005 (CfvT versus Cfv 3-18). The error bars indicate standard deviations.