FIG 8.

Pathogenicity of ΔC-CHIKV determined by studies in the IFNAR^−/− mouse model. IFNAR^−/− mice (6 weeks old; n = 6 per group) were injected subcutaneously in the ventral/lateral side of the hind foot with 10² PFU of WT CHIKV, 10⁵ PFU of ΔC-CHIKV, and 2% FBS–DMEM (negative control). (A to C) Animal survival (A), footpad swelling (n = 6 feet per group) (B), and weight loss (C) were monitored daily until 14 or 16 days postinoculation. (D) Viremia titer postinoculation. Viremia from day 1 to day 5 postinoculation was measured by qRT-PCR. (E) Images of feet on day 5 postinoculation. In panels B to D, data represent means ± SD for groups of mice, and the horizontal dotted line represents the limit of detection. Student’s t tests were used to determine differences between two groups, and a Kruskal-Wallis test followed by Dunn’s test was used for multiple comparisons. One, two, three, and four asterisks indicate statistical differences between indicated groups with P values of <0.05, <0.01, <0.001, and <0.0001, respectively. ns, not significant.