Fig 1.

Suppression of nuclear translocation of NF-κB by wild-type and inlC.K173A strains of L. monocytogenes. HeLa cells were either left uninfected or were infected for 5 h with the wild-type (wt), ΔinlC, or inlC.K173A bacterial strain. After infection, cells were treated or not for 30 min with 25 ng/ml TNF-α. After fixation and labeling, cells were analyzed by confocal laser scanning microscopy, as described in Materials and Methods. (A) Representative images of HeLa cells subjected to various infection conditions. Asterisks indicate cells containing intracellular L. monocytogenes, as indicated by decoration with F-actin. Note that TNF-α treatment caused an increase in the amount of nuclear NF-κB in uninfected cells and that this increase was inhibited by infection with the wild-type or inlC.K173A bacterial strain. (B) Quantification of the effect of bacterial infection on nuclear translocation of NF-κB. The fraction of NF-κB in the nucleus of uninfected or infected cells was quantified as described in Materials and Methods. Statistical analysis by ANOVA indicated that P was <0.0001. *, P < 0.05 relative to condition b (uninfected cells treated with TNF-α).