CD4 and HIV infectious disease: The expression of virus from unintegrated DNA in resting CD4+ T cells infected with WT or IN-deficient reporter viruses was reported by Trinité et al. [42] using two systems: cells preactivated with anti-CD3/CD28 antibodies, and cells pretreated with IL-4, which renders quiescent lymphocytes permissive to HIV infection without changing the differentiation state [43].