FIG. 6.

Vpr requires an intact HIV-1 LTR to induce expression from integration-defective HIV-1. (A) Schematic diagram of lentiviral vectors expressing luciferase under the control of various promoters. For the CMV- and Rh-MLV-driven luciferase lentivirus vectors, there is a 133-bp deletion in the U3 region of the HIV-1 LTR from −145 to −8, encompassing the TATA start site. (B) HeLa cells (2 × 10⁴) were infected with integrase-defective lentiviral vectors expressing luciferase under the control of the HIV-1 LTR, the CMV promoter, or the Rh-MLV LTR as indicated (25 ng of p24 antigen) and were coinfected with either HR-EGFP or HR-Vpr vector (200 ng of p24 antigen). The fold induction was calculated as the level of luciferase activity (mean ± standard deviation of three independent experiments) in the HR-Vpr vector-infected cultures relative to the HR-EGFP vector-infected cells.