Role of APOBEC3 in in vivo Restriction of Retrovirus Infection

描述(申请人提供)：在整个进化过程中，感染剂感染了原核生物和真核生物。事实上，生物体和它们的感染体之间存在共同进化，在宿主中产生保护性反应，并由感染体对它们采取适应性对策。一种病毒限制系统是由载脂蛋白B编辑复合体3(A3)家族蛋白质所赋予的，它使单链DNA中的脱氧胞苷残基脱氨，导致GC-AT转变。A3基因在拷贝数和序列方面都具有高度的多态，并显示出强烈的正选择证据，表明它们是针对病毒等感染性因素而进化的。类似的，逆转录病毒和其他病毒显示出脱氨基足迹，这表明它们反过来受到A3蛋白的选择压力，并表明A3介导的病毒DNA脱氨基可能导致耐药和免疫逃逸变异。虽然人们对A3蛋白及其在病毒限制中的作用已经有了很多了解，但大多数研究都是在培养细胞中进行的，通常使用从患者组织中分离的病毒的过度表达的蛋白质和序列分析，或者在人类原代细胞中的实验因存在7个人类A3基因而变得复杂，其中许多基因在相同的细胞类型中表达。事实上，虽然A3B、A3D、A3F、A3G和A3H在过度表达时都会限制HIV和其他病毒的表达，但它们在体内控制感染的作用尚不清楚。我们的实验室率先使用体内小鼠模型来研究A3蛋白如何限制逆转录病毒的感染。我们已经开发了基因敲除小鼠和最近表达单个人A3蛋白的基因工程动物，以研究小鼠乳腺肿瘤病毒和小鼠白血病病毒的感染。在这里，我们建议使用这些小鼠模型来研究单个人类A3蛋白如何在限制体内感染、塑造病毒进化以及影响逆转录病毒和其他病毒的免疫逃逸和耐药变异体的发展中发挥作用。这些研究将增加我们对A3蛋白在体内的作用机制的了解，并为抗病毒药物治疗的测试提供模型。

DESCRIPTION (provided by applicant): Infectious agents have infected prokaryotes and eukaryotes throughout evolution. Indeed, there is co-evolution among organisms and their infectious agents, with development of protective responses in the hosts and adaptive countermeasures to them by the infectious agents. One system of viral restriction is conferred by the Apolipoprotein B editing complex 3 (A3) family of proteins, which deaminate deoxycytidine residues in single-stranded DNA leading to GC-to-AT transitions. A3 genes are highly polymorphic both with regard to copy number and sequence and show strong evidence of positive selection, indicating that they are evolving in response to infectious agents like viruses Similarly, retroviruses and other viruses show deamination footprints suggesting they in turn are under selective pressure by A3 proteins and it has been suggested that A3-mediated deamination of viral DNA could lead to both drug-resistanct and immune escape variants. While much has been learned about A3 proteins and their roles in virus restriction, most studies have been carried out in cultured cells, often using over- expressed proteins and sequence analysis of viruses isolated from patient tissue or experiments in human primary cells are complicated by the presence of 7 human A3 genes, many of which are expressed in the same cell types. Indeed while A3B, A3D, A3F, A3G and A3H all restrict HIV and other viruses when over-expressed, there role in control of infection in vivo remains unclear. Our lab pioneered the use of in vivo mouse models to study how A3 proteins restrict infection by retroviruses. We have developed knockout mice and more recently genetically engineered animals that express individual human A3 proteins to study infection by mouse mammary tumor virus and murine leukemia virus. Here, we propose to use these mouse models to study how individual human A3 proteins function in to restrict in vivo infection, shape virus evolution and affect the developmen of immune escape and drug-resistant variants of retroviruses and other viruses. These studies will thus add to our understanding of A3 proteins mechanism of action in vivo as well as provide models for testing anti-viral drug therapies.