Experimental design DEF201 dose range titration experiment. Hamsters were weighed on the morning prior to the day of infection and grouped (n = 15 for drug treatment groups, 26 for the placebo group) so that the average hamster weight per group across the entire experiment varied by less than 5 grams. Varying pfu amounts of DEF201, the rAd EV control virus, or saline placebo treatments were administered in a single i.n. dose 24 h prior to challenge with ,5 pfu of PICV. Five animals from each group were sacrificed on day 7 of infection. Serum was collected for assaying ALT activity, and virus titers were determined for liver, spleen, and serum samples as described above. The remaining 10 animals (21 for the placebo group) were observed 21 days for mortality and weighed individually every 3 days starting on day 0. Sham-infected normal controls (n = 3) were included for comparison.