WT, B cell deficient μMT, or BCR transgenic MD4tr C57BL/6 mice were inoculated in the left rear footpad with 1,000 PFU of AF15561 or 181/25. At 28 dpi, (A) CHIKV RNA in the right ankle was quantified by RT-qPCR, and (B) CHIKV-specific IgG in the serum was quantified by a whole virion-based ELISA. Data are from two or more independent experiments. P values were determined by one-way ANOVA with a Tukey’s multiple comparison test. ****, P < 0.0001.