FIG. 4.

Undetectable HIV-1 Tat transactivation of LTR promoter in undifferentiated primary monocytes. (A and B) Monocytes and Hut/CCR5 cells (A) and macrophages (B) were transfected with pLTR-luc or cotransfected with pTat by nucleofection. Luciferase activity of cell lysates was measured 48 h posttransfection. All data are means ± standard deviations. cps, counts per second. (C) Nucleofection efficiency of macrophages. M-CSF-induced macrophages were nucleofected with pmax-GFP, and GFP expression was measured 24 h postnucleofection by flow cytometry. The gray peak represents mock-transfected control cells; the open peak defined by the bold line represents GFP-positive cells. MFI, mean fluorescence intensity (x axis). The y axis represents relative cell numbers. One representative experiment out of at least three is shown.