CD4 and HIV-1 infection: First, in order to analyze HIV-1 infection under HSP conditions, we infected CD4+ T cells with two minimal lentiviral vectors encoding a GFP marker gene under the control of either the HIV-1 LTR (Lenti LTR-GFP) or the EF-1α promoter (Lenti EF-GFP) (Figure 2A).