GFAP and infection: To quantify changes in the astrocyte population, we used HALO image analysis software and determined that the glial fibrillary acidic protein (GFAP) expression levels in the 3 brain regions combined were significantly higher at 14 dpi than the comparable brain regions of uninfected control animals (n = 3; P < 0.0001) and 7 dpi (P = 0.014), indicating astrocyte activation with infection (Figure 3, A–C, and E).