Fig. 1.

IpaC-NP is secreted and can functionally complement ΔipaC for invasion and phagosomal escape. (A) HeLa cells were infected with the indicated strains at an MOI of 10:1 and subsequently incubated for 1.5 h in medium containing gentamicin before enumeration of bacterial CFU. Values represent the means of the invasion efficiencies (normalized to the WT) for three independent experiments. (B) J774 cells were infected and then incubated for 1.5 h in medium containing gentamicin, with or without chloroquine, before determination of bacterial CFU. % vacuolar escape was calculated for each strain, and values represent the means for three independent experiments. **, P < 0.01. (C) Type III secretion of bacterial proteins was induced in the presence of Congo red for the indicated times. Supernatants from induced cultures were precipitated with TCA and analyzed by immunoblot analysis for IpaC (bl-15). Data are representative of two independent experiments.