Mock-infected or WNV-infected mice were exsanguinated and perfused with PBS, 4% paraformaldehyde, pH 7.3. Brains were embedded in paraffin and 10-mm sections were prepared and stained with hematoxylin and eosin (H&E) by the UW histology pathology laboratory. Sections were analyzed using a Nikon Eclipse E600 microscope (UW Keck microscope facility).