CD4⁺ T lymphocytes infected with HIV-1 express ULBP-2 in a Vpr-dependent manner. Human primary CD4⁺ T lymphocytes were mock-infected or infected with infectious CCR5-tropic HxBru.ADA.GFP or HxBru(Vpr-)ADA.GFP at an MOI of 0.5. After 5 days, mock-infected or GFP-expressing infected CD4⁺ T lymphocytes were monitored for expression of NKG2D ligands by flow cytometry using specific mAbs directed against ULBP-1, -2, and -3 and appropriate fluorochrome-conjugated secondary reagents. The histogram with the dashed line represents cells stained with the isotype control Abs; the filled histogram represents mock-infected cells, and the histograms with the bold and dotted lines represent, respectively, Vpr⁺ (HIV WT) and Vpr-defective (HIVΔVpr) HIV-infected cells, as indicated. MFI values were calculated by subtracting the corresponding isotype control values. Results shown are representative of the data obtained from 5 different donors.