Review Question - QID 108505

A 9-month-old baby boy is brought to his pediatrician due to poor feeding and fewer bowel movements. His father notes that he has been less active and is having difficulty with movements such as rolling over. Vital signs are normal, and physical exam is notable for weak sucking reflex, ptosis, and decreased eye movements. In addition, the baby has generalized weakness and flushed skin. Stool samples are collected, treatment is started immediately, and the baby’s condition improves. The results of the stool studies return several days later and show gram-positive, anaerobic rods. The toxin most likely responsible for this baby’s condition acts through which mechanism?