Human immunodeficiency virus type 1 Vpu has a CD4- and an envelope glycoprotein-independent function.
Vpu is a 16-kDa membrane-associated phosphoprotein that is expressed from the same, singly spliced message as the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein precursor, gp160. Previous studies suggest that Vpu functions in the late stages of viral replication, possibly in virus egression from the cell. Recently, it has been demonstrated that Vpu functions to allow gp160 to be more efficiently processed by disrupting CD4-gp160 complexes generated by transfection of HeLa cells. We show here that the lack of expression of intact Vpu results in a 90% reduction in infectious virus produced over a single round of replication from HeLa cells in the absence of CD4 expression. This reduction persists when HIV-1 particles are pseudotyped with the HIV-2 or amphotropic murine leukemia virus envelope glycoprotein. Pulse-chase analysis of HIV-1 capsid protein (p24) in the absence of CD4 and envelope glycoprotein demonstrates that the rate of virus release is reduced when Vpu is not expressed. Our findings indicate that Vpu has a function involving particle release not dependent on CD4 or envelope glycoprotein expression.
McArdle Laboratory for Cancer Research, University of Wisconsin, Madison 53706.
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Panganiban
D015704:CD4 Antigens / Q000378:metabolism; D002459:Cell Fusion; D003001:Cloning, Molecular; D015686:Gene Products, env / Q000378:metabolism; D016655:HIV Core Protein p24 / Q000378:metabolism; D015497:HIV-1 / Q000502:physiology*; D006367:HeLa Cells; D054298:Human Immunodeficiency Virus Proteins; D006801:Humans; D066298:In Vitro Techniques; D009154:Mutation; D014162:Transfection; D014759:Viral Envelope Proteins / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins / Q000502:physiology*; D014779:Virus Replication; D000086082:Viroporin Proteins
D015704:CD4 Antigens; D015686:Gene Products, env; D016655:HIV Core Protein p24; D054298:Human Immunodeficiency Virus Proteins; D014759:Viral Envelope Proteins; D054334:Viral Regulatory and Accessory Proteins; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins