Extended pre-exposure prophylaxis experiment. The design was similar to the DEF201 titration experiment with the following differences. Hamsters were weighed on the morning of initial pretreatment (day 214 relative to the infection) and grouped (n = 15 per group). Groups were treated once i.n. with 10 8 pfu of DEF201, rAd EV control virus, or saline placebo. Treatments were given 14 or 7 days prior to challenge with ,5 PFU of PICV. Animals were observed for 28 days post-challenge for mortality.