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. 2020 Sep 22;16(9):e1008852. doi: 10.1371/journal.ppat.1008852

Fig 2. The GTD is required for typhlitis in murine infection.

Fig 2

a) Schematic of non-lethal mouse model of CDI. Swiss Webster mice, excluding those in the uninfected control group, were pretreated with an antibiotic cocktail in drinking water for three days (gray box, days -6 to -3), then orally dosed with 1 mg clindamycin on day -1 to induce dysbiosis. On day 0, mice were orally challenged with C. difficile 630Δerm (wild-type, n = 7), C. difficile 630ΔermΔtcdA (tcdA deletion mutant, n = 7), C. difficile 630ΔermΔtcdA GTD::D270N (GT-defective mutant, n = 7) or sterile PBS for the uninfected control group (n = 3). Fecal pellets were collected daily to analyze C. difficile burden and caeca were harvested on day 5 for histological analysis. b) C. difficile burden per 200 μL inoculum quantified for each bacterial strain. Statistical analysis between C. difficile strains was analyzed using one-way ANOVA with Tukey’s multiple comparison test (ns, non-significant). c) Daily C. difficile burden measured from selective culture of fecal samples. Graph displays each replicate with connecting line indicating the mean per group at each time point. Statistical analysis between groups was performed on each day for days 1–4 via Kruskal-Wallis test (ns, non-significant) and on day 5 via Kruskal-Wallis with multiple comparisons (**p<0.01 between wild-type and GT-defective mutant, all other comparisons non-significant). d) Histopathological score for combined inflammatory cell infiltrates (0–3), mucosal hypertrophy (0–3), epithelial disruption (0–3) and submucosal edema (0–3), with each pathological feature scored from normal (0) to severe (3) on H&E-stained caecal slides. Statistical analysis performed via one-way ANOVA with Tukey’s multiple comparison test (ns, non-significant; ***p<0.001, ****p<0.0001). Representative H&E image of caecal section from e) uninfected control group, f) wild-type group, g) tcdA deletion mutant group, and h) GT-defective mutant group. Images were taken with x20 magnification, and scale bar indicates 100 μM. Black arrows indicate apoptotic cell sloughage, black bar with asterisk indicates submucosal edema.