Role of Vif in HIV-1 Replication/AIDS

HIV-1 vif基因对于非允许性细胞（NP）（包括CD 4阳性T淋巴细胞和巨噬细胞以及一些白血病T细胞系）的感染性病毒生产至关重要，但在其他称为允许性（P）的细胞系中不相关。NP细胞可以用来自P细胞的vif缺失的HIV-1感染，但感染的NP细胞仅释放非感染性病毒体。这些非感染性病毒粒子不能通过靶细胞中的vif表达来拯救，并且它们被认为具有降低逆转录效率的缺陷。我们和另一个实验室最近显示了NP表型在PxNP异核体中的优势，这表明NP细胞含有一种可以抑制HIV-1的因子，并且这种因子被Vif抵消。使用人淋巴细胞cDNA文库在酵母双杂交筛选与Vif作为诱饵，我们现在已经确定了干扰素诱导蛋白Sp140作为一个很好的候选人，这个NP因子。简言之，Sp140存在于所有测试的NP细胞中，但不在P细胞中。Sp140存在于核体（NB）中，核体含有通过添加泛素相关蛋白Sumo-1共价修饰的几种蛋白质。Sp140在Hela-CD 4细胞中的表达诱导至少一种蛋白质的类小泛素化，并且Vif的共表达阻断这种诱导。HIV-1感染诱导Sp140迁移到细胞质中，并与Vif部分共定位。我们建议：（i）验证Vif与Sp140和其他潜在的合作伙伴的遗传，免疫学和生化方法的相互作用。(ii)分析Sp140亚型和其他潜在的Vif伴侣对Vif缺失的HIV-1的抑制能力。(iii)确定Vif与Sp140和其他潜在伙伴相互作用的活性位点。(iv)通过双向电泳，鉴定SP 140诱导的P细胞中的sumoylated和非sumoylated蛋白，并确定Vif如何影响这些诱导。同样，确定NP细胞中Vif的表达是否改变了蛋白质类小泛素化，以及在P或NP细胞中产生的vif缺失的HIV-1是否含有任何类小泛素化蛋白。(iv)有趣的是，单纯疱疹病毒1型ICPO蛋白靶向NB，并特异性地引起一些sumoylated NB蛋白的消除，CMV、EBV、腺病毒和沙粒病毒编码的蛋白似乎具有类似的活性。确定这些其他病毒蛋白的表达是否将NP细胞转化为P细胞。这项工作可能为艾滋病药物开发揭示一个新的靶点。

The HIV-1 vif gene is essential for infectious virus production by nonpermissive cells (NP), which include CD4-positive T-lymphocytes and macrophages and some leukemic T-cell lines, but is irrelevant in other cell lines that are termed permissive (P). NP cells can be infected with vif-deleted HIV-1 derived from P cells, but the infected NP cells release only noninfectious virions. These noninfectious virions cannot be rescued by vif expression in target cells, and they are believed to have a defect that reduces efficiency of reverse transcription. We and another laboratory recently showed the dominance of the NP phenotype in PxNP heterokaryons, suggesting that NP cells contain a factor that can inactivate HIV-1 and that this factor is counteracted by Vif. Using a human lymphocyte cDNA library in a yeast two-hybrid screen with Vif as bait, we have now identified the interferon-inducible protein Sp140 as an excellent candidate for this NP factor. Briefly, Sp140 occurs in all tested NP cells but not in P cells. Sp140 occurs in nuclear bodies (NBs) that contain several proteins covalently modified by addition of the ubiquitin-related protein Sumo-1. Expression of Sp140 in Hela-CD4 cells induces sumoylation of at least one protein, and coexpression of Vif blocks this induction. HIV-1 infections induce Sp140 emigration to the cytosol and its partial colocalization with Vif. We propose: (i) Verify Vif interaction with Sp140 and with other potential partners by genetic, immunological, and biochemical methods. (ii) Analyze Sp140 isoforms and other potential Vif partners for their abilities to inactivate vif-deleted HIV-1. (iii) Identify active sites for interaction of Vif with Sp140 and with other potential partners. (iv) By two-dimensional electrophoresis, identify sumoylated and non-sumoylated proteins induced in P cells by Sp140, and determine how Vif influences these inductions. Similarly, determine whether Vif expression in NP cells alters protein sumoylation and whether vif-deleted HIV-1 made in P or NP cells contains any sumoylated protein. (iv) Interestingly, the herpes simplex virus type 1 ICPO protein targets NBs and specifically causes the elimination of some sumoylated NB proteins, and proteins encoded by CMV, EBV, adenoviruses and arenaviruses appear to have similar activities. Determine whether expression of these other viral proteins converts NP cells to P. This work may unveil a novel target for drug development in AIDS.