CD4 and infection: To determine if HSV-2 infection favors infiltration of Fas- and FasL-positive immune cells into the spinal cord, we prepared the spinal cord cell suspensions at day 5 and 9 post-infection and assessed the presence of Fas and FasL on CD4+ T-cells (CD3+/CD4+ cells), CD8+ T-cells (CD3+/CD8+ cells) and monocytes (CD45hi+/CD192+/CD11b+/Ly6C+ cells) using flow cytometry.