Figure 3. Regulation of C. perfringens toxin production by the VirS/VirR TCRS. (A) western blot analysis of CPB production by overnight vegetative cultures of type C strain CN3685, an isogenic virR null mutant (VirR knockout) or the virS/virR complementing strain (VirR/pTS405). For comparison, the migration of purified CPB is also shown in the left lane of the blot. (B) western blot analyses of ETX production by 4 h vegetative broth cultures of type D strain CN3718, the isogenic virR null mutant (VirR knockout) or the complementing strain (VirR/pTS405). Reproduced with permission from refs. 54 and 61.