The effect of vpu on HIV-1-induced syncytia formation.

To investigate the role of vpu in the cytopathicity of human immunodeficiency type 1 (HIV-1), the MT4 CD4+ T-cell line was infected with viruses that were isogenic except for their ability to produce the vpu protein. The experiments described here demonstrate that expression of vpu reduces HIV-1 cytopathic effects by decreasing the rate of syncytia formation. By reducing the concentration of gp 120 at the cell surface, vpu limits cell killing by syncytia formation.