Figure 4.

Evaluation of IgG anti-BclA3_CTD and anti-C. difficile spores R20291 and R20291ΔbclA3 titers on mice serum. ELISA plates coated with 50 ng/well of purified BclA3_CTD (A) or 1.6 × 10⁷ spores/well of C. difficile R20291 or R20291ΔbclA3 spores (B) were incubated with 1:100 of mice serum immunized on days 0 (Pre-Immune serum, PI), 13 (d13, before second immunization), 27 (d27, before third immunization) or day 41 (d41, before infection with C. difficile spores). The assessment of specific IgG anti-BclA3_CTD and anti-spores was obtained using the secondary antibody 1:5000 anti-IgG mouse HRP. Results are reported as optical density (OD) units at 492 nm. The geometric mean plus standard error of the mean for each cohort are shown. Comparisons between days in the same group were obtained using two-way ANOVA and Tukey’s multiple comparison test; statistical significance (p < 0.05) is indicated by asterisks. * p < 0.05 and **** p < 0.0001. No significance (n.s).