Figure 4.

Virulence assays in a BALB/c mice model. Groups of four-week-old mice (n = 4) were inoculated by intranasal route with 106 PFU/10 µL of VACV-BABV strain clones 2 and 3 (large-plaque) and clone 1 (small plaque), and VACV-GOBV clone 2 (large plaque) and clone 3 (small plaque). VACV-WR was used as virulent control, and the negative control group was inoculated with PBS. No mice infected with small plaque clones died while the mice infected with large plaque clones had survival rates of 0% and 50%, showing variations in survival rates between the clones (A); Uninfected mice (negative control) and animals infected with small plaque clones gained weight, while mice infected with large plaque clones lost weight similarly to mice infected with virulent control VACV-WR (B). Ruffling fur and arching back were observed in mice infected with large plaque clones on day 4 p.i. No clinical signals were observed in mice infected with small plaque clones from the same strain. Balanopostitis and periocular alopecy were observed only in mice infected with virulent control VACV-WR on day 3 p.i. No clinical signals were observed in control mice inoculated with PBS.