HIV Evolution Driven by Intracellular Defenses

描述（由申请人提供）：APOBEC 3家族包含7种不同的蛋白质（APOBEC 3A [A3 A]至A3 H），其可作为前病毒基因组的强突变体。辅助HIV蛋白Vif抵消了一些但不是所有APOBEC 3变体的抗病毒活性。尽管全球HIV-1大流行是由非B亚型，特别是C亚型驱动的，但关于Vif作用模式的大多数数据来自与A3 G结合的B亚型分子克隆。然而，APOBEC 3分子不仅在催化活性和表达方面不同，而且在对HIV-1 Vif介导的降解的敏感性方面也不同。我们假设广谱Vif活性是传播/建立感染的驱动力，而次优Vif活性对于疾病后期逃逸变体和多样化的出现至关重要。这一假设将在三个互补的具体目标，使用既定的和新的检测方法进行测试。我们将对大流行、非大流行和患者来源的Vif等位基因的功能进行全面分析（目标1），剖析Vif进化与患者中偏斜的前病毒档案之间的关系（目标2），并通过在存在增加的APOBEC 3表达的情况下传代HIV来确定Vif在强制选择实验中的可塑性（目标2）。最后，我们将在人源化小鼠模型中使用编码突变Vif变体的病毒来确定哪种APOBEC 3限制CXCR 4和CCR 5的病毒传播（目的3）。这些实验将共同确立Vif作为毒力因子的推定作用，创建“基因型-表型”测定以预测亚型特异性背景下的Vif活性，并鉴定与体内限制和多样化相关的特异性APOBEC 3蛋白。这些知识将有助于发现针对这种不同病毒-宿主界面的药物，并通过识别病毒逃逸高风险患者来改善现有的治疗方案。

DESCRIPTION (provided by applicant): The APOBEC3 family comprises seven different proteins (APOBEC3A [A3A] to A3H), which may act as strong mutators of proviral genomes. The accessory HIV protein Vif counteracts the antiviral activity of some but not all APOBEC3 variants. Although the global HIV-1 pandemic is driven by non-B subtypes, in particular subtype C, most data concerning the mode of action of Vif have been derived from subtype B molecular clones in conjunction with A3G. APOBEC3 molecules, however, differ not only in catalytic activity and expression but also in susceptibility to HIV-1 Vif mediated degradation. We hypothesize that broad spectrum Vif activity is the driving force for transmission/establishment of infection while suboptimal Vif activity is essential for emergence of escape variants and diversification in the later stages of disease. This hypothesis will be tested in three complementary specific aims using established and new assays. We will perform a comprehensive analysis of the function of pandemic, non-pandemic and patient- derived Vif alleles (Aim 1), dissect the relationship between Vif evolution and skewed proviral archives in patients (Aim 2), and determine the plasticity of Vif in forced selection experiments by passaging HIV in the presence of increasing APOBEC3 expression (Aim 2). Lastly, we will establish which APOBEC3 restricts viral spread of CXCR4 and CCR5 using viruses encoding mutant Vif variants in a humanized mouse model (Aim 3). These experiments will collectively establish the putative role of Vif as virulence factor, create "genotype to phenotype" assays to predict Vif activity in a subtype specific context and identify specific APOBEC3 proteins relevant for restriction and diversification in vivo. This knowledge will help in the discovery of drugs targeting this diverse viral-host interface and improve the already available treatment options by identifying patients at high risk for viral escape.