Lavallée C, Yao X J, Ladha A, Göttlinger H, Haseltine W A, Cohen E A
Département de Microbiologie et Immunologie, Faculté de Médecine, Université de Montréal, Quebec, Canada.
J Virol. 1994 Mar;68(3):1926-34. doi: 10.1128/JVI.68.3.1926-1934.1994.
The human immunodeficiency virus type 1 (HIV-1) particles consists of two molecules of genomic RNA as well as molecules originating from gag, pol, and env products, all synthesized as precursor proteins. The 96-amino-acid Vpr protein, the only virion-associated HIV-1 regulatory protein, is not part of the virus polyprotein precursors, and its incorporation into virus particles must occur by way of an interaction with a component normally found in virions. To investigate the mechanism of incorporation of Vpr into the HIV-1 virion, Vpr- proviral DNA constructs harboring mutations or deletions in specific virion-associated gene products were cotransfected with Vpr expressor plasmids in COS cells. Virus released from the transfected cells was tested for the presence of Vpr by immunoprecipitation with Vpr-specific antibodies. The results of these experiments show that Vpr is trans-incorporated into virions but at a lower efficiency than when Vpr is expressed from a proviral construct. The minimal viral genetic information necessary for Vpr incorporation was a deleted provirus encoding only the pr55gag polyprotein precursor. Incorporation of Vpr requires the expression but not the processing of gag products and is independent of pol and env expression. Direct interaction of Vpr with the Pr55gag precursor protein was demonstrated by coprecipitation experiments with gag product-specific antibodies. Overall, these results indicate that HIV-1 Vpr is incorporated into the nascent virion through an interaction with the Gag precursor polyprotein and demonstrate a novel mechanism by which viral protein can be incorporated into virus particles.
1型人类免疫缺陷病毒（HIV-1）颗粒由两个基因组RNA分子以及源自gag、pol和env产物的分子组成，所有这些分子均以前体蛋白的形式合成。96个氨基酸的Vpr蛋白是唯一与病毒体相关的HIV-1调节蛋白，它不是病毒多蛋白前体的一部分，其掺入病毒颗粒必须通过与病毒体中通常存在的一种成分相互作用来实现。为了研究Vpr掺入HIV-1病毒体的机制，将在特定病毒体相关基因产物中含有突变或缺失的Vpr前病毒DNA构建体与Vpr表达质粒在COS细胞中共转染。用Vpr特异性抗体通过免疫沉淀法检测转染细胞释放的病毒中是否存在Vpr。这些实验结果表明，Vpr是反式掺入病毒体的，但其效率低于从前病毒构建体表达Vpr时的效率。Vpr掺入所需的最小病毒遗传信息是一个仅编码pr55gag多蛋白前体的缺失前病毒。Vpr的掺入需要gag产物的表达但不需要其加工，并且与pol和env的表达无关。通过与gag产物特异性抗体的共沉淀实验证明了Vpr与Pr55gag前体蛋白的直接相互作用。总体而言，这些结果表明HIV-1 Vpr通过与Gag前体多蛋白相互作用掺入新生病毒体，并证明了一种病毒蛋白可掺入病毒颗粒的新机制。
