Intermittent viral replication in the foot tissue.

Neonate C57BL/6 mice (6–8 days old) were infected by intradermal injection with 10⁶ PFU of CHIKV. The mice were sacrificed at 6, 29 or 50 dpi. (A, B) Expression of the positive strand and negative strand RNA in the ipsilateral feet was assessed by qRT–PCR using primers and probes specific for the nsP1 gene. (C, D) Expression of the positive strand and negative strand RNA in the ipsilateral feet was detected by qRT–PCR using primers and probes specific for the E1 gene. Dashed line, average value of control mice inoculated with BHK-21 cell supernatant. n = 5 mice per group. All data are presented as the mean ± SD. *: p< 0.05; **: p< 0.01; ***: p< 0.001; statistical relevance was determined by one-way ANOVA.