FIG 7.

CD4 but not tetherin downmodulation is impaired by an inhibitor of the cullin-RING E3 ubiquitin ligase machinery. CD4⁺ T cells activated with CD3/CD28 beads were transduced with VSV-G-pseudotyped HIV-1 NL4-3 UEOel IRES-eGFP constructs containing the indicated vpu and/or nef alleles. Two days postransduction, either DMSO or the small-molecule inhibitor MLN4924 (500 nM) was added. Cells were examined for eGFP and tetherin (A) or CD4 (B) surface expression via flow cytometry 24 h later. Values are averages (±SEM) from three independent experiments. ***, P < 0.001.