FIG 4.

Survival of immunized mice challenged with TcdA and TcdB. (A) An immunization and challenge schedule for mice is shown. C57BL/6 mice (n = 10/group) were immunized as described in the text and rested for 8 weeks before being challenged intraperitoneally with a lethal dose of C. difficile toxin. (B and C) Animals immunized with pARBD-NQ (B) or pBRBD-NQ (C) were challenged with 300 ng of TcdA or 150 ng of both TcdA and TcdB, respectively. i.p., intraperitoneal; ctrl, control. *, P ≤ 0.05; ***, P ≤ 0.001.