Fig. 4.

Effect of S. typhi infection of cultured intestinal epithelial cells. Henle-407 cells were infected with S. typhi, its isogenic cdtB mutant, or the cdtB mutant carrying a plasmid encoding either wild-type CdtB or a mutant lacking the putative sec-dependent secretion signal (pcdtB^Δ1-22). Cells were examined 72 h after transfection under a phase microscope (A) or processed to measure DNA content by flow cytometry (B) as indicated in Materials and Methods. The peaks corresponding to cells in G₀/G₁ (G0-G1), S, or G₂ (G2-M) are indicated. (Scale bar, 50 μm.)