Infiltration of leukocytes and viral load in the brains of WT and db / db mice after WNV infection. (A) Cryopreserved brain sections from WNV-infected WT and db/db mice at day 8 after infection were stained with hematoxylin and eosin (H & E) and antibodies against CD45 (Green, white arrows and enlarged inset of the arrowed box) and CD8 (Red, white arrows and enlarged inset of the arrowed box). Black arrows and enlarged inset of the arrowed box on the H & E stained sections identify leukocytes infiltrating into the meninges of the WT brains. The photomicrographs demonstrate representative images obtained from two independent experiments (n = 4 per group). Bars, 20 μm. (B) Quantitative representation of total numbers of CD45 and CD8 positive cells from 15 different brain areas per section (total 2 brain sections per mice) from two independent experiments (n = 4 per group). *P <0.05. (C) Brain viral load was determined in WT and db/db mice, at days 4, 6, and 8 after infection by plaque assay using Vero cells and is reported as PFU per gram of tissue. Data represents the mean ± SEM, representing two independent experiments (n = 7-11 per group). *P <0.05. PFU, plaque-forming units; SEM, standard error of mean.