Relative Resistance of HLA-B to Downregulation by Naturally Occurring HIV-1 Nef Sequences.
Relative Resistance of HLA-B to Downregulation by Naturally Occurring HIV-1 Nef Sequences.
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DOI：
10.1128/mbio.01516-15
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发表时间：
2016-01-19
期刊：
影响因子：
6.4
通讯作者：
Ueno T
中科院分区：
文献类型：
--
作者：
Mahiti M;Toyoda M;Jia X;Kuang XT;Mwimanzi F;Mwimanzi P;Walker BD;Xiong Y;Brumme ZL;Brockman MA;Ueno T
HIV-1 Nef与HLA-A和HLA-B的胞质区域结合，并从病毒感染细胞的表面下调这些分子，从而逃避CD 8 + T细胞的免疫检测。HLA胞质区域内的多态性残基可能影响Nef的下调活性。然而，HLA多态性对主要Nef分离株识别的影响仍然难以捉摸，负责下调HLA-A与HLA-B的特定Nef区域也是如此。在这里，我们研究了从慢性HIV-1亚型B感染受试者中分离的46个Nef克隆下调病毒感染细胞表面各种HLA-A、HLA-B和HLA-C分子的能力。总体而言，HLA-B表现出更大的耐Nef介导的下调比HLA-A，无论检查的细胞类型。正如预期的那样，没有Nef克隆下调HLA-C。重要的是，患者来源的Nef克隆下调HLA-A和HLA-B的不同能力与HIV感染的靶细胞对表达HIV-1 Gag特异性T细胞受体的效应细胞识别的敏感性呈负相关。Nef密码子功能分析表明，202位的氨基酸变异（Nef-202）差异性地影响下调HLA-A和HLA-B的能力，这一观察结果随后通过使用通过定点诱变构建的Nef突变体的实验得到证实。计算机模拟和诱变分析进一步表明，Nef-202可能与HLA-A的C-末端Cys-Lys-瓦尔残基相互作用，这在HLA-B中不存在。总之，结果表明Nef内的天然多态性调节其与HLA胞质尾中的天然多态性的相互作用，从而影响HLA下调的效率和随后由HIV特异性T细胞识别。因此，这些结果扩展了我们对逆转录病毒免疫逃避这一复杂途径的理解。适应性免疫系统对遗传多样性病原体的识别代表了宿主防御的主要策略;然而，诸如HIV-1的病原体可以逃避这些反应以实现持续感染。HIV-1 nef基因和HLA I类基因座分别是病毒和宿主最多样化的基因。HIV-1 Nef蛋白与HLA-A和HLA-B的胞质区域相互作用，并下调这些分子以逃避细胞免疫。通过结合分子、遗传和计算机分析，我们证明了患者来源的Nef克隆比HLA-B分子更有效地下调HLA-A。这反过来又调节HIV特异性T细胞识别HIV感染细胞的能力。我们还鉴定了Nef密码子202和HLA胞质基序（GG 314，315和CKV 339 -341）的天然多态性位点，这些位点有助于Nef对HLA的差异下调。我们的研究结果强调了HIV-1和人类免疫系统之间可能导致发病机制的新相互作用。
HIV-1 Nef binds to the cytoplasmic region of HLA-A and HLA-B and downregulates these molecules from the surface of virus-infected cells, thus evading immune detection by CD8+ T cells. Polymorphic residues within the HLA cytoplasmic region may affect Nef’s downregulation activity. However, the effects of HLA polymorphisms on recognition by primary Nef isolates remain elusive, as do the specific Nef regions responsible for downregulation of HLA-A versus HLA-B. Here, we examined 46 Nef clones isolated from chronically HIV-1 subtype B-infected subjects for their ability to downregulate various HLA-A, HLA-B, and HLA-C molecules on the surface of virus-infected cells. Overall, HLA-B exhibited greater resistance to Nef-mediated downregulation than HLA-A, regardless of the cell type examined. As expected, no Nef clone downregulated HLA-C. Importantly, the differential abilities of patient-derived Nef clones to downregulate HLA-A and HLA-B correlated inversely with the sensitivities of HIV-infected target cells to recognition by effector cells expressing an HIV-1 Gag-specific T cell receptor. Nef codon function analysis implicated amino acid variation at position 202 (Nef-202) in differentially affecting the ability to downregulate HLA-A and HLA-B, an observation that was subsequently confirmed by experiments using Nef mutants constructed by site-directed mutagenesis. The in silico and mutagenesis analyses further suggested that Nef-202 may interact with the C-terminal Cys-Lys-Val residues of HLA-A, which are absent in HLA-B. Taken together, the results show that natural polymorphisms within Nef modulate its interaction with natural polymorphisms in the HLA cytoplasmic tails, thereby affecting the efficiency of HLA downregulation and consequent recognition by HIV-specific T cells. These results thus extend our understanding of this complex pathway of retroviral immune evasion. Recognition of genetically diverse pathogens by the adaptive immune system represents a primary strategy for host defense; however, pathogens such as HIV-1 can evade these responses to achieve persistent infection. The HIV-1 nef gene and the HLA class I locus rank among the most diverse genes of virus and host, respectively. The HIV-1 Nef protein interacts with the cytoplasmic region of HLA-A and HLA-B and downregulates these molecules to evade cellular immunity. By combining molecular, genetic, and in silico analyses, we demonstrate that patient-derived Nef clones downregulate HLA-A more effectively than HLA-B molecules. This in turn modulates the ability of HIV-specific T cells to recognize HIV-infected cells. We also identify a naturally polymorphic site at Nef codon 202 and HLA cytoplasmic motifs (GG314,315 and CKV339–341) that contribute to differential HLA downregulation by Nef. Our results highlight new interactions between HIV-1 and the human immune system that may contribute to pathogenesis.