1. The envelope glycoprotein of human immunodeficiency virus type 2 enhances viral particle release: a Vpu-like factor?
- Author
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Bour S, Schubert U, Peden K, and Strebel K
- Subjects
- Brefeldin A, Cyclopentanes pharmacology, Gene Products, nef metabolism, Gene Products, vif metabolism, Gene Products, vpr metabolism, Genes, Viral, Glycoproteins drug effects, Glycoproteins genetics, HIV Seropositivity blood, HIV Seropositivity immunology, Human Immunodeficiency Virus Proteins, Humans, Mutation, Viral Envelope Proteins drug effects, Viral Envelope Proteins genetics, Viral Regulatory and Accessory Proteins drug effects, Virion metabolism, nef Gene Products, Human Immunodeficiency Virus, vif Gene Products, Human Immunodeficiency Virus, vpr Gene Products, Human Immunodeficiency Virus, Glycoproteins metabolism, HIV-2 metabolism, Viral Envelope Proteins metabolism, Viral Regulatory and Accessory Proteins metabolism
- Abstract
The Vpu protein is a human immunodeficiency virus type 1 (HIV-1)-specific accessory protein that is required for the efficient release of viral particles from infected cells. Even though HIV-2 does not encode Vpu, we found that this virus is nevertheless capable of efficiently releasing virus particles. In fact, the rate of virus release from HeLa cells transfected with a full-length molecular clone of HIV-2, ROD10, was comparable to that observed for the vpu+ HIV-1 NL4-3 isolate and was not further enhanced by expression of Vpu in trans. However, consistent with previous observations showing that HIV-2 particle release is Vpu responsive in the context of HIV-1/HIV-2 chimeric constructs; exchanging the gag-pol region of NL4-3 with the corresponding region from pROD10 rendered the resulting chimeric virus Vpu responsive. Our finding that the responsiveness of HIV-2 particle release to Vpu is context dependent suggested the presence of a Vpu-like factor(s) encoded by HIV-2. Using chimeric proviruses encoding HIV-2 gag and pol in the context of the HIV-1 provirus that were coexpressed with subgenomic HIV-2 constructs, we found that the HIV-2 envelope glycoprotein had the ability to enhance HIV-2 particle release with an efficiency comparable to that of the HIV-1 Vpu protein. Conversely, inactivation of the HIV-2 env gene in the original ROD10 clone resulted in a decrease in the rate of viral particle release to a level that was comparable to that of Vpu-deficient HIV-1 isolates. Providing the wild-type envelope in trans rescued the particle release defect of the ROD10 envelope mutant. Thus, unlike HIV-1, which encodes two separate proteins to regulate virus release or to mediate viral entry, the HIV-2 Env protein has evolved to perform both functions.
- Published
- 1996
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