CD4 and infection: Since the difference was significant already before SIVmac239wt infection (Fig 1E), but not before HSV-2 challenge (S1 Fig), the data suggest that HSV-2 infection increases the number of blood CD4+ T cells and the rate of the initial CD4+ T cell decline in HSV-2+/SIVmac239wt+ macaques is similar to that of HSV-2- /SIVmac239wt+.