<p>(A) NIH3T3 cells stably expressing mCherry-actin were infected with EPEC expressing GFP for 3 h and imaged live for 45 min. Scale bar, 10 μm. (B) mCherry-actin expressing cells were infected with the indicated strains for 3 h and imaged live for 18–20 min. 15–20 bacteria per host cell for each strain were tracked, and data from representative cells were plotted such that points starting at t = 0 were centered at the origin. (C) Bacterial motility rates were quantified from cells infected as in (B). Each bar represents the mean speed (+/- SE) of bacteria on 6–20 host cells (95–293 total bacteria). ** p<0.01, *p<0.05 (ANOVA, Tukey post-hoc tests). (D) The fraction of pedestals that were considered moving was quantified, using the average speed of the pedestal deficient counterpart strain as a minimum cutoff to define movement. Each bar represents the mean (+/- SE) from 227–320 pedestals. p = 0.3 (Fisher’s exact test). (E) Directional persistence of pedestals was calculated by dividing the maximum displacement by the total path length for pedestals considered to be moving. Each bar represents the mean (+/- SE) for 205–297 pedestals on 19–20 cells. p = 0.1 (unpaired <i>t</i> test) (F) Cells were infected with EHEC strains with or without EspF<sub>U</sub> and imaged live. Each bar represents the mean speed (+/- SE) of bacteria on 6 cells (60 bacteria). *p<0.05 (ANOVA, Tukey post-hoc test).</p
