CD4 and infection: To determine if the CD4 depleted mice that were found to display these signs of neurological disease had more severe CNS inflammation than the non-depleted mice, which in general displayed only moderate clinical signs of disease, we performed hematoxylin and eosin (H&E) staining on sections of the brains of depleted and control mice at day 8 post-infection (n = 4–5 per group) (S1 Fig).