Vpr is a small amino acid protein encoded by the human immunodeficiency virus type 1 (HIV-1). Vpr prevents the proliferation of HIV-1-infected cells by causing cells to accumulate in the G2 stage of the cell cycle,and is a cytostatic, rather than cytotoxic agent. the accumulation in G2 is mediated by the ability of Vpr to prevent activation of the mitotic cyclin-dependant kinase. However, the mechanism of mitotic block is different from normal G2 DNA damage checkpoint control. Although Vpr expressing T-cells do not pass through mitosis, they continue to synthesize DNA and increase in ploidy. Thus HIV-1 encodes a protein which can decouple S phase from mitosis in human cells. We will show data that suggest that one role of Vpr is to maximize viral production by manipulation of the cell cycle in the face of cytolysis in vivo.

Cyclin-Dependent Kinases/METABOLISM Enzyme Activation G2 Phase Gene Products, vpr/*PHYSIOLOGY HIV Infections/*METABOLISM/PATHOLOGY HIV-1/*GENETICS Human Mitosis Ploidies ABSTRACT

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