SAMHD1 and infection: To determine whether Vpx-mediated degradation of endogenous SAMHD1 occurred during the course of spreading infections of replication-competent virus in CD4+ T lymphocytes, freshly collected, and negatively selected, Con-A stimulated rhesus macaque CD4+ T cells were infected with WT SIVmac239 at a multiplicity of infection (MOI) = 0.2.