FIG 3.

PSII/α-GC vaccination leads to enhanced protection against C. difficile disease. (A to G) Age- and sex-matched naive B6 mice were cefoperazone treated and then mock infected or infected with 10⁴ live C. difficile spores. Mice previously immunized with PSII alone, PSII plus α-GC, or α-GC and PSII 1 week apart were also cefoperazone treated and infected. Graphs show the percentage of original weight, which was obtained daily and for the duration indicated. Data show the results of two pooled experiments with n = 5 for each group except for the naive-infected, α-GC- and then vehicle-treated, and PSII/α-GC groups (n = 10). Statistical significance was determined by repeated-measure ANOVA and Tukey’s multiple-comparison test (*, P < 0.05; **, P < 0.01). (H) Fecal pellets collected 2 days after infection were used to determine bacterial load. In group A, zero counts were detected (limit of detection in assay, 10²). (I) ELISA measurement of C. difficile-specific IgG1 in response to the various vaccination modalities used. In panels H and I, significance was determined by one-way ANOVA with Tukey’s multiple-comparison test (*, P < 0.05; **, P < 0.01). (J and K) Naïve (n = 4) and PSII/α-GC-immunized (n = 5) mice, antibiotic treated and infected with 5 × 10⁴ spores. Weight loss and survival are depicted. Numbers above bars on the left are the numbers of remaining live animals in the group. A Mantel-Cox log rank test was used to detect differences between groups subject to Kaplan-Meier survival analysis.