Figure 3.

Analysis of In Vivo Virulence of the Mutant Deletion Viruses

C57BL/6 mice were inoculated (i.n.) at various virus doses; after infection, weight and signs of illness were evaluated daily until day 15. (A and B) Mice infected with 5 × 10⁶ PFU/mouse (WR WT, WR-Luc, WR-Δ3, and WR-Δ4) were evaluated for (A) percent weight loss, (B, top) signs of illness, and (B, bottom) percent survival. ^†Indicates that all mice in the group were sacrificed because of viral infection. (C and D) Mice infected with 5 × 10⁷ PFU/mouse (WR-Δ3, WR-Δ4) were evaluated for (C) percent weight loss, (D, top), signs of illness, and (D, bottom) percent survival. Signs of illness were evaluated by assigning a score from 1 to 4 (1 = absence of illness and 4 = severe illness), considering loss of mobility, trouble breathing, hunched posture, absence of grooming, and inflammation of the eye membrane. Mice were sacrificed when they showed a body weight reduction >20% or had an illness score of 4. Data are shown as mean ± SD.