rAd-ABA protection of mice against systemic toxin challenges. PBS, rAd-GFP (10¹⁰ PFU) or rAd-ABA (10¹⁰ PFU) was i.v. administered 4 days before mice were challenged with a mix of TcdA and TcdB (25 or 250 ng of each toxin per mouse) and mouse survival was monitored. Overall mouse survival was analyzed by Kaplan-Meier survival curves. **P = 0.01 and ***P = 0.003.