Time is relative to the end of lethal inhalational challenge to B. anthracis. Animals (n = 18 in groups 1–3 and 5–7; n = 17 in group 4) were vaccinated 1 and 8 days post-challenge with serial dilutions of AV7909 (groups 1–5), a 1:16 dilution of AVA (group 6), or 0.5 mL of normal saline (group 7). Group 8 (n = 14) served as a positive control for lethal exposures to B. anthracis and were neither vaccinated nor treated with ciprofloxacin. Ciprofloxacin treatment started 1 day post-challenge and continued through 14 days post-challenge (groups 1–7); animals in group 8 (untreated control) were administered normal saline under the same regimen. The proportions of surviving animals in the groups vaccinated with 1:4 and 1:16 dilutions of AV7909 (groups 1 and 2) were significantly greater
(P = 0.0132 and P = 0.0007, respectively) than that in the group that received ciprofloxacin only (group 7).