Guinea pigs were challenged with 24 mipLD50 BoNT/A1 [1.7 guinea pig intramuscular (i.m.) LD50 (gpimLD50)] and treated 2 days later with vehicle (intraperitoneally; n = 14), a single dose of B8C1ad (0.02 mg/kg, intraperitoneally; n = 9), or multiple doses of B8C1ad (0.02 mg/kg) followed by supplemental treatments of B8C1ad at 5 and 8 days after intoxication (0.02 mg/kg, intraperitoneally; n = 18). Survival and CSS were evaluated at daily intervals. (A) Ten-day survival curves comparing vehicle, single-dose B8C1ad, and multiple-dose B8C1ad. (B) Median ± interquartile ratio (IQR) CSS scores. All data represent the aggregate of at least three experiments. Additional details of statistical comparisons are presented in table S3. **P < 0.01 and ****P < 0.0001.