Fig. 3: T4SS-mediated biofilm formation and conjugation by AIEC requires traVC_ICE.

A Biofilm formation by the different AIEC strains on epithelial cells. Immunofluorescence staining shows the cytoskeleton of Caco-2 epithelial cells in red with DAPI-stained nuclei in blue, infected with wild-type (wt) or isogenic mutant AIEC strains in green. Isogenic strains carrying vector controls were used when applicable. Each panel is representative of 45 images per group, n = 3 independent biological replicates. Scale bar is 100 µm. B Quantification of biofilm formation by each strain shown as a percentage relative to wt. Biofilms were quantified across 15 fields of view per trial over three independent experiments. Data is presented as mean values +/− SEM. Statistical significance was tested by Kruskal–Wallis test with Dunn’s multiple comparisons test. C Wt AIEC donor displayed higher conjugation relative to the isogenic mutants lacking different T4SS components. E. coli /pOX38 was used as a positive control. Data represent 21 biological replicates from 6 independent experiments. Outliers were removed using Grubb’s test. Data is presented as mean values +/− SEM. Statistical significance was tested by repeated measures one-way ANOVA with Dunnett’s multiple comparisons test comparing the different AIEC strains to wt, ****P < 0.0001. Source data are provided as a Source Data file.