Figure 7. Evaluation of extent of protection of WR or VVΔE3L pre-immunized ISG15+/+ and ISG15−/− mice after challenge with WR.

Four mice per group were first i.p, immunized with purified WR (2×10⁷ PFU/mouse) or VVΔE3L (10⁸ PFU/mouse), and 30 days later animals were i.n. challenged with 2×10⁷ PFU/mouse of purified WR. A–B. Mice were individually weighed daily, and mean percentage weight loss of each group (n = 4) was compared with the weight of mice taken prior to the booster. C–D. For each mouse signs of illness, such as ruffled fur and lack of activity, were monitored with the time and are given in arbitrary units.