FIG 3.

Leukocyte infiltration into the CNS is elevated in WNV-infected Il17a^−/− mice. Seven- to 9-week-old WT (C57BL/6J) and Il17a^−/− mice were challenged i.p. with WNV (1,000 PFU). (A and B) PBS-perfused brains were isolated at 6 dpi, and WNV antigen (green signal) and CD45 (leukocyte common antigen; red) (A) or CD11b (macrophage and microglial marker; red) (B) was detected with a Nikon A1R confocal microscope (original magnification, ×20). DAPI (blue signal) was used as a nuclear counterstain; representative images are shown. (C) Brain leukocytes isolated at 6 dpi were characterized by flow cytometry after probing with antibodies against WNV-E, CD45, CD4, CD8, and CD11b. The signal colors used in the dot plots and the percentages of positive cells within gated populations are shown on the right. The data represent the results of two independent experiments (n = 5 mice per group for each experiment). Boxes indicate CD45^hi cells, upper circles indicate CD3⁺ T cells, and lower circles indicate CD11b⁺ cells. (D and E) Expression of Ccl5 (D) and Ccr5 (E) genes at the mRNA level was measured by qPCR in the blood of WNV-infected mice at 2 and 4 dpi. (F to H) mRNA levels of Ccl5 (F), Cxcl10 (G), and Cxcr3 (H) genes were measured by qPCR in brains of WNV-infected mice at 8 dpi. The gene expression data were normalized to cellular β-actin mRNA and compared by two-tailed Student t tests; ns, no significant difference (P > 0.05).