Survival of bacteria in BMDM. BMDM were either pretreated or not pretreated with IFN-γ (50 ng/ml) for 24 h and subsequently infected with pYV+ or ΔyopH with a MOI of 5 (C) for 0.25 or three hours as described in Material and Methods. Numbers of bacteria were determined by a CFU assay. The data represent the CFU ± standard deviation of three independent experiments. All groups were compared for one point in time and asterisks indicate significant differences between the compared groups (p < 0.05, one-way ANOVA with Bonferroni correcctions).