Role of APOBEC3 in in vivo Restriction of Retrovirus Infection

描述（由申请人提供）：传染因子在进化过程中感染了原核生物和真核生物。事实上，生物体和它们的感染因子之间存在着共同进化，宿主产生了保护反应，感染因子对它们采取了适应性对策。载脂蛋白B编辑复合体3 （A3）蛋白家族赋予了一种病毒限制系统，该蛋白家族使单链DNA中的脱氧胞苷残基脱胺，导致gc到at的转变。A3基因在拷贝数和序列方面都具有高度多态性，并显示出强烈的正选择证据，表明它们是在对病毒等感染因子的反应中进化的。同样，逆转录病毒和其他病毒显示脱氨足迹，表明它们反过来受到A3蛋白的选择压力。有人认为，A3介导的病毒DNA脱氨可能导致耐药和免疫逃逸变异。虽然已经对A3蛋白及其在病毒限制中的作用有了很多了解，但大多数研究都是在培养细胞中进行的，通常使用过表达蛋白和从患者组织中分离的病毒的序列分析，或者在人类原代细胞中进行的实验，由于存在7种人类A3基因，其中许多基因在相同的细胞类型中表达，因此变得复杂。事实上，虽然A3B、A3D、A3F、A3G和A3H在过表达时都能抑制HIV和其他病毒，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的基因工程动物，表达个体人类A3蛋白，以研究小鼠乳腺肿瘤病毒和小鼠白血病病毒的感染。在此，我们建议使用这些小鼠模型来研究个体人类A3蛋白如何在体内限制感染，塑造病毒进化，影响逆转录病毒和其他病毒的免疫逃逸和耐药变体的发展。因此，这些研究将增加我们对A3蛋白在体内作用机制的理解，并为测试抗病毒药物治疗提供模型。

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.