FIG 7.

Mouse mortality after systemic inoculation of wild-type and mutant TcdB. Intraperitoneal inoculation of mice with 100 ng of either wild-type TcdB or TcdB-L543A resulted in 100% mortality although the time to full mortality was delayed in mice treated with TcdB-L543A compared to those treated with wild-type TcdB (log rank test; P < 0.01). Inoculation of mice with 20 ng of TcdB led to 60% mortality, whereas the same dose of TcdB-L543A did not cause any mortality; although all mice displayed signs of systemic disease, they eventually recovered (P < 0.05). Mice inoculated with a glucosyltransferase-deficient TcdB variant (aTcdB) at a dose of 10 μg/mouse showed no sign of disease, and all mice survived (P < 0.01).