HIV-1 evolution driven by intracellular defenses

HIV-1进化由细胞内防御驱动

• 批准号: 7069062
• 负责人: Viviana A Simon
• 金额: $ 5.59万
• 依托单位: AARON DIAMOND AIDS RESEARCH CENTER
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7069062
• 关键词: HIV infections; amination; aminohydrolases; binding sites; biochemical evolution; clinical research; drug resistance; enzyme activity; fluorescent dye /probe; gene expression; gene induction /repression; gene mutation; host organism interaction; human immunodeficiency virus 1; human tissue; molecular genetics; protein degradation; virulence; virus DNA; virus cytopathogenic effect; virus genetics; virus infection mechanism

DESCRIPTION (provided by applicant): Retroviruses have devised a number of strategies to evade cellular mechanisms aimed at preventing retroviral infection. HIV-1 expresses Vif, a protein that counteracts the antiviral activity of the cytidine deaminases APOBEC3G and APOBEC3F. The nucleotide composition of the HIV-1 genome suggests, however, that protection from host-mediated viral cDNA deamination may not be absolute. In preliminary studies, we showed that vif genes encoding proteins that fail to degrade APOBEC3G, APOBEC3F or both can be detected in vivo. The loss of Vif function was mapped to single nucleotide substitutions. These studies indicate that natural variation in Vif function may profoundly impact the extent and direction of viral sequence evolution within HIV-1 infected individuals. The experiments proposed herein will determine the extent to which host mechanisms aimed to prevent retroviral infection, in fact, contribute to viral diversification and pathogenesis. We will analyze the fitness of viruses expressing Vif proteins that are closely related but differ in their ability to neutralize APOBEC3G or APOBEC3F activities. We will also test if variation in Vif function may be beneficial for viral adaptation under certain circumstances (e.g., in the presence of antiretroviral drugs) by determining whether cytidine deamination by APOBEC3G or APOBEC3F selects for certain drug resistance mutations. The pattern of hypermutations associated with partial protection from cytidine deamination will be correlated to HIV fitness. Since APOBEC3 enzymes induce hypermutations in different dinucleotide contexts the understanding of how activity against one enzyme but not the other is maintained is relevant for viral evolution. We will conduct structure function studies to determine whether domains other than the Vif SOCS box motif are necessary and essential for Vif mediated specific neutralization of APOBEC3 enzymes. Finally, we will assess the impact of reverse transcription and APOBECS-driven mutagenesis on loss of Vif function. We will determine the rate of Vif inactivation as result of either reverse transcriptase or cytidine deamination induced mutations on a single cell level using assays based on fluorescence tagged APOBEC3G degradation. Variation in Vif function may influence the pathogenicity of HIV-1 by rendering its genome more or less resistant to deaminase activity and these studies have the potential to reveal how Vif mediated protection from cytidine deamination is modulated in vivo.

描述（由申请人提供）：逆转录病毒设计了许多策略来逃避旨在预防逆转录病毒感染的细胞机制。HIV-1表达Vif，一种抵消胞苷脱氨酶APOBEC 3G和APOBEC 3F的抗病毒活性的蛋白质。然而，HIV-1基因组的核苷酸组成表明，对宿主介导的病毒cDNA脱氨基的保护可能不是绝对的。在初步研究中，我们发现，vif基因编码的蛋白质不能降解APOBEC 3G，APOBEC 3F或两者都可以在体内检测到。Vif功能的丧失被定位为单核苷酸取代。这些研究表明，Vif功能的自然变异可能会深刻影响HIV-1感染者体内病毒序列进化的程度和方向。 本文提出的实验将确定旨在预防逆转录病毒感染的宿主机制实际上对病毒多样化和发病机制的贡献程度。我们将分析表达Vif蛋白的病毒的适应性，Vif蛋白密切相关，但在中和APOBEC 3G或APOBEC 3F活性的能力上不同。我们还将测试Vif功能的变化是否在某些情况下对病毒适应有益（例如，在抗逆转录病毒药物的存在下），通过确定APOBEC 3G或APOBEC 3F是否选择某些耐药突变的胞苷脱氨基作用。与胞苷脱氨基的部分保护相关的超突变模式将与HIV适应性相关。由于APOBEC 3酶在不同的二核苷酸背景下诱导超突变，因此了解如何维持针对一种酶而不是另一种酶的活性与病毒进化相关。我们将进行结构功能研究，以确定Vif SOCS盒基序以外的结构域是否是Vif介导的APOBEC 3酶特异性中和所必需的。最后，我们将评估逆转录和APOBECS驱动的突变对Vif功能丧失的影响。我们将使用基于荧光标记的APOBEC 3G降解的测定法，在单细胞水平上确定逆转录酶或胞苷脱氨诱导突变导致的Vif失活率。Vif功能的变化可能会影响HIV-1的致病性，使其基因组或多或少地抵抗脱氨酶活性，这些研究有可能揭示Vif介导的胞苷脱氨基保护是如何在体内调制。