Figure 3.

Schematic overview of the experimental design for the prevention of C. difficile infection in a murine model. C57BL/6 mice were nasally immunized three times (42, 28 and 14 days before challenge with C. difficile R20291 spores) with PBS, spores of B. subtilis PY79, purified BclA3_CTD or spores of B. subtilis displaying the chimera protein CotBΔ-BclA3_CTD (AZ703). Prior to the infection with C. difficile R20291, the animals were submitted to an antibiotic cocktail (days 4–6 before challenge) and clindamycin administration (1 day before challenge). On day 0, mice were infected with 5 × 10⁷ of C. difficile R20291 spores and were monitored from day 0 to day 5 for CDI symptoms. Serum was collected one day before each immunization, two days before C. difficile infection and on the day of sacrifice.