FIG 5.

IL-18 release and bacterial exit from epithelial cells for the S. Typhimurium mutants. HeLa and C2BBe1 epithelial cells were infected with wild-type (WT) S. Typhimurium strain SL1344 or the indicated gene deletion mutants. (A) At 10 h p.i., cell culture supernatants were collected from HeLa cells and apical supernatants from polarized C2BBe1 cells. The amount of secreted IL-18 was quantified by an ELISA. Shown are box plots of data from ≥4 independent experiments. Asterisks indicate data significantly different from those for wild-type infection. (B) At 7 h p.i. (HeLa) or 8 h p.i. (C2BBe1), gentamicin-containing medium was removed and replaced with gentamicin-free medium for 1 h. Supernatants were collected, and extracellular CFU were enumerated after serial dilution and plating. Each data point is for one well on a 24-well plate, and data from ≥3 independent experiments are shown (2 to 3 wells per experiment). The horizontal bar indicates the mean. Asterisks indicate data significantly different from those for wild-type infection.