Indeed, prior work has demonstrated that intravenous SIVmac239 inoculation results in elevated viral loads within 1 to 2 wk of infection,81–84 which is consistent with our finding here of peak viremia by week 2 p.i. We also observed depletion of peripheral CCR5+ CD4+ T cells during acute SIV infection and restoration to baseline levels with early ART initiation, which is consistent with prior reports on the CCR5-tropism of SIV,85,86 depletion of the CCR5+ CD4+ T cell compartment during acute SIV infection,87 and restoration of CCR5+ CD4+ T cells after ART.88 Here, CD4 is linked to infection.