FIG 5 .

The virulence of L. monocytogenes ΔchiA mutants is restored in mice lacking iNOS. (A) L. monocytogenes intravenous infection. C57BL/6 mice were intravenously infected with 2 × 10⁴ CFU L. monocytogenes wild-type or ΔchiA mutant bacteria. The scatter plot shows CFU obtained from the livers and spleens of five individual mice at 72 h postinfection; the data are representative of two independent experiments. Solid lines and brackets represent the means and standard errors of the means, respectively, for the data points in each group. ***, statistically significant value (P < 0.0001) for ΔchiA bacteria in both the liver and the spleen after 72 of infection compared to results for the wild type using a one-way analysis of variance with Dunnett’s posttest (GraphPad V.5.0A). (B) Intravenous infection of C57BL/6 NOS2^−/− mice lacking iNOS. C57BL/6 NOS2^−/− mice were intravenously infected with 2 × 10² CFU L. monocytogenes wild-type or ΔchiA mutant bacteria [the infectious dose was adjusted to reflect the ~100-fold increase in susceptibility to L. monocytogenes infection for mice lacking iNOS (36)]. The scatter plot shows CFU obtained from the livers and spleens of five individual mice at 72 h postinfection; the data are representative of two independent experiments. Solid lines and brackets represent the means and standard errors of the means, respectively, for the data points in each group. No significant statistical difference was detected between the bacterial burdens of mice infected with ΔchiA bacteria for either organ (P > 0.05) compared to findings for the wild type using a one-way analysis of variance with Dunnett’s posttest (GraphPad V.5.0A).