Figure 9.

Effect of pretreatment with IFNγ on PhoPQ induction. RAW264.7 macrophages were either pretreated for 18 h with 100 U of IFNγ (triangles) or were left untreated (squares). The cells were infected with Salmonella Typhimurium transformed with phoP::GFP and analyzed by flow cytometry as above. Where indicated, the cells were in addition treated with CcA immediately after invasion (as for the open squares in Figures 7 and 8). (A) Quantitation of viable bacteria recovered from infected cultures, performed by cell lysis and plating of lysates on LB agar plates; (B) total fluorescence. (C) Percentage of inhibition of phoP::GFP expression by IFN-γ, CcA and the combination of both IFN-γ and CcA. (D) Fluorescence normalized per bacterium, per cell. Data shown in A, B, and D are representative of five similar experiments and C is a compilation of five independent experiments.