Figure 4.

C57BL/6 mice were infected with CHIKV by three different routes, and their footpad swelling and tissue viral distributions are compared. C57BL/6 mice were infected with 1,000 PFU CHIKV SL15649 intramuscularly in the right calf (i.m. R calf), subcutaneously in the skin of the right calf (s.c. right calf), or in the right leg footpad (f.p.). (A) Footpad swelling measurements were taken at 0, 3, and 5 dpi using calipers. (B) Serum from CHIKV-infected mice was isolated at 3 dpi, and viremia was measured by limiting dilution plaque assay on confluent monolayers of Vero cells. (C–F) At 5 dpi, mice were sacrificed and whole tissues were dissected and homogenized in 1 ml cell culture media. Infectious viral levels in the ankle and calf muscle tissue homogenate were measured by limiting dilution plaque assay on confluent monolayers of Vero cells (n = 5).