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）：逆转录病毒已经设计了许多策略来逃避旨在防止逆转录病毒感染的细胞机制。 HIV-1表达VIF，这是一种抵消胞苷脱氨酶Apobec3g和apobec3f的抗病毒活性的蛋白质。但是，HIV-1基因组的核苷酸组成表明，免受宿主介导的病毒cDNA脱氨基的保护可能不是绝对的。在初步研究中，我们表明可以在体内检测到无法降解apobec3g，apobec3f或两者的VIF基因。 VIF功能的丧失被映射到单核苷酸取代。这些研究表明，VIF功能的自然变化可能会深刻影响HIV-1感染个体内病毒序列演化的程度和方向。 本文提出的实验将确定旨在防止逆转录病毒感染的宿主机制的程度，实际上有助于病毒多样化和发病机理。我们将分析表达与密切相关但中和APOBEC3G或APOBEC3F活动的能力不同的VIF蛋白的病毒的适应性。我们还将测试通过在某些情况下（例如，在存在抗逆转录病毒药物的情况下）通过确定APOBEC3G或APOBEC3F的胞苷脱氨酸是否选择某些药物耐药性突变来选择胞苷脱氨酸，是否可能对病毒适应有益。与胞丁脱氨基脱氨基的部分保护相关的高温模式将与HIV适应性相关。由于APOBEC3酶在不同的二核苷酸环境中诱导过度充血，因此了解对一种酶的活动方式而不是另一种酶的理解与病毒进化有关。我们将进行结构函数研究，以确定除VIF SOCS盒基序以外的其他域是否是必需的，对于VIF介导的APOBEC3酶的特异性中和必不可少。最后，我们将评估逆转录和APOBEC驱动诱变对VIF功能丧失的影响。我们将使用基于荧光标记的APOBEC3G降解的测定法确定VIF灭活率在单个细胞水平上诱导的突变。 VIF功能的变化可能会通过使其基因组或多或少地抗脱氨酶活性来影响HIV-1的致病性，并且这些研究可能会揭示VIF如何在体内调节VIF介导的胞苷脱氨基的保护。