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 生成大量变异体，并频繁进行重组洗牌 这些突变进一步增加了遗传多样性。中的变化 病毒种群使亚群的变种存活下来 当环境变化时，繁荣。这一点得到了戏剧性的证明 在人类缺陷病毒(HIV)感染的研究中。AZT抗性 这些人在接受AZT治疗后产生了HIV毒株 治疗。病毒可以产生变种来逃避宿主免疫系统 最近发现的艾滋病毒逃逸突变体就是一个例证 通过改变表位部分逃避免疫监视 被细胞毒性T细胞识别。 逆转录病毒重组发生在逆转录过程中，这是 病毒DNA拷贝是从病毒粒子RNA中产生的。因此，它是 病毒复制的固有部分。我建议从三个方面进行研究 逆转录病毒重组。同源病毒间的重组 在一个种群中，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。 在目标1中，具有极端同源性的向量将被用于研究 重组。这是为了模拟病毒类中的重组 物种。这些实验将告诉我们， 病毒种群中不同变种之间的基因交换。 在目标2中，实验旨在询问病毒是否具有巨大的 通过重组可以很容易地挽救病变。之间的重组 两种有病变的病毒以及一种野生型病毒和病毒之间的病毒 将对有损伤的患者进行研究。 在目标3中，逆转录病毒载体来自两个基因不同的 病毒将被用来研究两者之间可能的重组 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.