Titration of protection conferred by passive transfer of anti-L1 monoclonal antibody in VACV IHD-J mouse model. Groups of seven (50 μg dose) to 10 (5 and 0.5 μg groups) mice were inoculated s. c. with purified anti-L1 MAb-10F5 diluted in PBS. The next day, all 27 mice were challenged with 2 × 106 PFUPFU of virus intransally. Mice were monitored for 20 days. Moribund animals, or animals that lost more than 30% of their starting weight, were euthanized. Days 0-14 are shown. No additional animals succumbed after day 12.