DISSECTING THE MECHANISMS OF RETROVIRAL RECOMBINATION

突变和重组是逆转录病毒用来 增加病毒种群的变异。 高突变率 产生了大量的变异体， 这些突变进一步增加了遗传多样性。 变化 病毒群体允许变异的亚群存活， 随着环境的变化而变化。 这是戏剧性的证明 人类免疫缺陷病毒（HIV）感染的研究。 抗AZT 在这些人接受AZT后， 治疗 病毒可以产生变异以逃避宿主免疫系统 例如最近发现的HIV逃逸突变体， 通过改变表位部分逃避免疫监视 被细胞毒性T细胞识别。 逆转录病毒的重组发生在逆转录过程中，这是逆转录过程中的一个步骤。 其中病毒DNA拷贝由病毒体RNA产生。 因此有 病毒复制的内在部分。 我建议研究三方面 逆转录病毒重组。 同源病毒间的分离 在一个群体中，那些介于具有大病变的病毒和野生型之间的病毒 病毒，以及基因不同的病毒之间的那些将被研究。 将使用基于脾坏死病毒的载体和辅助细胞系 研究一轮逆转录病毒复制过程中的重组。 在目的1中，具有极端同源性的载体将用于研究 重组 这是为了模拟病毒准- 物种 这些实验将告诉我们 病毒群体中不同变异体之间的遗传交换。 在目标2中，实验旨在询问是否具有大的 通过重组可以容易地挽救损伤。 之间的重组 两种病毒之间的病变以及野生型病毒和病毒 将对病变进行研究。 在目标3中，逆转录病毒载体来源于两种遗传上不同的 病毒将被用来研究两种病毒之间可能的重组。 不同的病毒

Mutation and recombination are two mechanisms used by retroviruses to increase variation in the viral population. High rate of mutation generates a large pool of variants, and frequent recombination shuffles these mutations to further increase genetic diversity. Variation in the viral population allows a subpopulation of variants to survive and prosper when the environment changes. This is dramatically demonstrated in the study of human deficiency virus (HIV) infection. AZT resistant strains of HIV were generated after the individuals received AZT treatment. Virus can generate variants to evade the host immune system as exemplified by the recently discovered HIV escape mutant that partially escape the immune surveillance by altering the epitopes recognized by cytotoxic T cells. Retroviral recombination occurs during reverse transcription, a step in which a viral DNA copy is generated from virion RNA. Therefore, it is an intrinsic part of viral replication. I propose to study three aspects of retroviral recombination. Recombination between homologous viruses in one population, those between viruses with large lesions and wildtype viruses, and those between genetically distinct viruses will be studied. A Spleen necrosis virus based vector and helper cell line will be used to study recombination during one round of retroviral replication. In aim 1, vectors with extreme homology will be used to study recombination. This is to mimic recombination within a viral quasi- species. These experiments will tell us the efficiency and extent of genetic exchange between different variants in a viral population. In aim 2, experiments are directed to ask whether viruses with large lesions can be easily rescued by recombination. Recombination between two viruses with lesions as well as between a wildtype virus and virus with lesions will be studied. In aim 3, retroviral vectors derived from two genetically distinct viruses will be used to study the possible recombination between two different viruses.