The APOBEC/Vif Conflict and HIV Pathogenesis

描述(申请人提供)：人类细胞已经发展出许多抑制病毒复制的机制，而病毒已经进化出不同的策略来抵抗它们的影响。病毒和宿主之间的这种平衡体现在APOBEC家族胞苷脱氨酶和HIV编码的调节蛋白Vif的抗HIV特性上。培养的细胞实验表明，至少有三种APOBEC蛋白，APOBEC3G(HA3G)，APOBEC3F(HA3F)和APOBEC3B(HA3B)可以深刻地抑制HIV感染。病毒抑制是通过依赖于DNA编辑(即，对新生的第一链逆转录本进行C-to-U脱氨基，表现为编码链的G-to-A突变)和/或非依赖(即，防止反向转录积聚)机制来实现的。HIV Vif的保护作用是通过连接hA3G/F和一个类似cullin5-SCF的E3泛素连接酶之间的相互作用来发挥的，从而使hA3G/F蛋白在产生病毒的细胞中被降解。因此，hA3G/F和HIV VIF之间的动态变化可能是HIV传播和感染结果的关键决定因素。最近的研究让人们得以洞察这些因素的相对重要性。然而，已报道的hA3G基因表达和编码区DNA多态与感染后进展为艾滋病之间的关联是复杂和矛盾的。这些相互矛盾的发现表明，这些先天宿主因素的影响还没有得到充分的研究。这项建议的总体目标是从根本上了解艾滋病毒VIF/HA3G/F/B冲突及其对感染的易感性和抵抗力以及艾滋病进展速度的影响。我们将测量hA3G/F/B基因在表型定义的细胞群体中的表达(mRNA和蛋白质)，定位它们在组织细胞亚群中的表达，并检测影响艾滋病易感性和抗药性的遗传和单倍型关联的遗传变异性(DNA多态)及其遗传和单倍型关联。我们将使用从参加自然历史队列研究的个人(即互委会和WIHS)获得的信息和临床样本进行这项工作。我们将使用严格的统计学方法来证明(或反驳)实验测量(即，特定表型和位置的细胞的基因表达[包括mRNA和蛋白质]的丰度、G-to-A超突变的程度、病毒序列多样化以及v/f和hA3G/F/B基因和蛋白质的变异)与HIV致病机制之间的相关性。关于Vif/hA3G/F/B冲突如何影响HIV感染的这一新发现的知识，应该被证明有助于寻找利用这种固有的抗病毒防御机制的活性的新药治疗方法。

DESCRIPTION (provided by applicant): Human cells have developed many mechanisms to inhibit viral replication, and viruses have evolved diverse strategies to resist their effects. This balance between the virus and its host is exemplified by the anti-HIV properties of the APOBEC family of cytidine deaminases and the HIV-encoded regulatory protein, Vif. Cultured cell experiments have shown that at least three APOBEC proteins, APOBEC3G (hA3G), APOBEC3F (hA3F), and APOBEC3B (hA3B) can profoundly inhibit HIV infection. Viral suppression is mediated through both DNA editing-dependent (i.e., C-to-U deamination of nascent first strand reverse transcripts that is manifested as G-to-A mutation of the coding strand) and/or -independent (i.e., prevention of reverse transcript accumulation) mechanisms. The protective role of HIV Vif is exerted through bridging an interaction between hA3G/F and a cullin5-SCF-like E3 ubiquitin ligase such that the hA3G/F proteins are degraded in virus-producing cells. Thus, the dynamic between hA3G/F and HIV Vif might be a critical determinant of HIV transmission as well as the outcome of infection. Recent work has allowed insights into the relative importance of these factors. Nevertheless, the reported associations between hA3G gene expression and DNA polymorphism in the coding region and progression to AIDS after infection are complex and contradictory. These conflicting findings suggest that the effects of these innate host factors have not been investigated adequately. The overall goal of this proposal is to achieve a fundamental understanding of the HIV Vif/hA3G/F/B conflict and its influence on susceptibility and resistance to infection and the rate of progression to AIDS. We will measure hA3G/F/B gene expression (both mRNA and protein) in phenotypically defined cell populations, localize their expression in cell subsets in tissue, and examine genetic variability (DNA polymorphisms) and their genetic and haplotype associations that influence susceptibility and resistance HIV infection and progression to AIDS. We will perform this work with the information and clinical samples obtained from individuals enrolled in natural history cohort studies (i.e., the MACS and WIHS). We will use rigorous statistical methods to prove (or disprove) correlations between experimental measurements (i.e., the abundance of gene expression [both mRNA and protein] by cells of defined phenotype and location, the extent of G-to-A hypermutation, viral sequence diversification, and variation in the v/fand hA3G/F/B genes and proteins) and HIV pathogenesis. This newfound knowledge of how the Vif/hA3G/F/B conflict affects HIV infection should prove useful in the search for new drug treatments that leverage the activity of this innate antiviral defense mechanism.