GENETIC STRUCTURE OF MURINE RETROVIRUSES

鼠逆转录病毒的遗传结构

• 批准号: 3809596
• 负责人: L H EVANS
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3809596
• 关键词: Retroviridae disease; chimeric proteins; gene expression; genetic recombination; genetic strain; laboratory mouse; monoclonal antibody; mouse leukemia; murine leukemia virus; nucleic acid sequence; oncogenes; oncogenic virus; point mutation; tissue /cell culture; viral leukemogenesis; virus antigen; virus envelope; virus genetics; virus infection mechanism; virus protein; virus replication

Retroviruses undergo frequent genetic alterations which in many instances may contribute to the pathogenicity of the viruses. Murine retroviruses, for example, readily undergo recombination with endogenous sequences of mice, leading to host range variants. Such variants have been directly implicated in the activation of cellular oncogenic genes. Variants which escape the host immune response or which exhibit an altered pathogenicity may be the result of point mutation of lentiviruses, such as the equine infectious anemia virus (EIAV) and the human immunodeficiency virus (HIV). This project is focussed on the occurrence and mechanisms of genetic alteration in retroviruses as well as the consequences of such alterations. In previous work we have utilized a number of monoclonal antibodies (mAbs) to identify and isolate recombinant host range variants from mice which were inoculated with murine leukemia viruses (MuLVs), or from mice which harbor endogenous MuLVs and spontaneously generate such variants. We have now identified three antigenic classes of the recombinant viruses which encompass all of the isolates examined. Structural analyses of the recombinants suggests that the three antigenic classes correspond to three distinct classes of endogenous gene sequences. Furthermore, we have found that different MuLVs recombine with different sets of endogenous sequences to preferentially generate distinct classes of viruses. Utilizing in vitro-constructed chimeric MuLVs, we found that the selectivity for a particular class of recombinant maps to the same regions of the genome previously found to influence the tissue-specific replication of the inoculated viruses. In preliminary experiments we have demonstrated pseudotyping of the inoculated virus resulting in an altered in vitro host range. Thus, it is possible that the generation of a particular recombinant influences the sites of replication of the inoculated virus. Alteratively, replication in different tissues may influence the class of recombinant viruses generated. Another aspect of this project has focussed on the determination of the point mutation rate of retroviruses. Previous estimates of the point mutation rate of retroviruses have not been carefully controlled for the number of replication cycles and/or the target size for mutation. By strictly controlling the number of replication cycles and directly examining the virion RNA genome, we have determined that the mutation rate for a murine retrovirus is approximately 20-fold slower than previous estimates reported in the literature.

逆转录病毒经历频繁的基因改变，在许多情况下 可能与病毒的致病性有关。小鼠逆转录病毒， 例如，很容易与内源序列重组 老鼠，导致宿主范围变异。这样的变种直接被 与细胞致癌基因的激活有关。其中的变种 逃避宿主免疫反应或表现出改变的致病性 可能是慢病毒的点突变的结果，比如马 传染性贫血病毒(EIAV)和人类免疫缺陷病毒(HIV)。 本课题主要研究遗传基因的发生和机制。 逆转录酶病毒的改变以及这种改变的后果。 在以前的工作中，我们已经利用了一些单抗(MAbs)。 鉴定和分离小鼠重组宿主范围变异体 接种了小鼠白血病病毒(MuLV)，或来自 保护内源性MULV，并自发地产生这些变种。我们有 现在鉴定了重组病毒的三个抗原类 包括所有被检查的分离物。的结构分析。 重组表明这三个抗原类对应于三个 不同类别的内源基因序列。此外，我们还发现 不同的MULV与不同的内源序列集重组 优先生成不同类别的病毒。利用中 体外构建的嵌合MULV，我们发现对一个 特定类别的重组映射到基因组的相同区域 先前发现影响组织特异性复制的 接种的病毒。在初步实验中，我们已经证明 接种病毒的伪分型导致体外宿主改变 射程。因此，有可能产生一种特定的重组 影响接种病毒的复制位置。或者， 不同组织中的复制可能会影响重组的类别 病毒产生了。 这个项目的另一个方面集中在确定 逆转录病毒的点突变率。之前对这一点的估计 逆转录病毒的变异率没有得到仔细的控制 复制周期数和/或突变的目标大小。通过 严格控制复制周期数，直接 检查病毒粒子RNA基因组，我们已经确定了突变率 对于小鼠逆转录病毒来说，速度大约是以前的20倍 文献中报告的估计值。