REPRESSION AND ACTIVATION OF PERSISTING HSV GENOMES

单纯疱疹病毒裂解基因表达的启动 通过VP16激活即刻早期(IE)转录 由输入病毒粒子提供。IE蛋白然后作用于诱导和 调节HSV基因组其余部分的表达。在.期间 潜伏期，病毒裂解基因表达不发生，基因组 以染色质包装的异构体成分存在。重新激活自 潜伏期可能涉及到基因组在缺乏 VP16。一种IE蛋白ICP0已被证明参与了 在几个模型系统中从延迟重新激活的过程。ICPO有 也被证明可以促进裂解病毒基因的表达。而它的 作用机制尚不清楚，它已被证明与一个 泛素水解酶。使用在子集上有缺陷的突变体 IE蛋白质提供了检测病毒基因表达和 组织中缺乏裂解基因表达的基因组持久性 文化。一个突变体d109不表达五种IE中的任何一种 蛋白质，完全无毒，并建立长期的 与细胞的关系。来自持久基因组的基因表达 被抑制，但可被ICP0诱导。因此， 在感染d109的组织培养细胞中发生的一些事件是 类似于体内潜伏基因组可能出现的情况。我们建议 ICP0的活性导致了细胞通路的变化 参与基因表达的抑制和去抑制。二 将研究的途径；组蛋白乙酰化途径和 泛素/蛋白酶体途径。提供的数据是ICP0的动作 类似于组蛋白去乙酰酶抑制剂曲古斯丁的作用 关于诱导被抑制的基因组，对细胞的影响 循环，以及细胞基因的诱导。与其他延迟模型不同 系统，建议的系统是非常服从量化的 生物化学和分子表征。拟议的具体目标 是；i.检查基因的表达和坚持的身体状态 病毒基因组。Ii)确定ICP0如何相对于以下各项改变此状态 乙酰化和蛋白酶体途径的抑制剂。三)确定 ICP0对宿主细胞基因表达和组蛋白的影响 修饰，并将这些与血管紧张素转换酶抑制剂的效果进行比较 乙酰化和蛋白酶体途径。和iv)确定是否在 乙酰化和蛋白酶体途径影响HSV感染 通往ICP0的路。这项研究的结果将为我们提供关于 ICP0影响细胞，以及HSV基因组如何被抑制和 保持潜伏状态，随后重新激活。

The initiation of herpes simplex virus lytic gene expression proceeds with the activation of immediate early (IE) transcription by VP16 supplied from the input virions. The IE proteins then act to induce and regulate the expression of the remainder of the HSV genome. During latency, viral lytic gene expression does not occur, and the genome persists as an episomal element packaged in chromatin. Reactivation from latency presumably involves activation of the genome in the absence of VP16. One IE protein, ICP0, has been shown to be involved in the process of reactivation from latency in several model systems. ICPO has also been shown to facilitate lytic viral gene expression. While its mechanism of action is unknown, it has been shown to interact with a ubiquitin proteinase. The use of mutants deficient in subsets of the IE proteins provides the means to examine viral gene expression and genome persistence in the absence of lytic gene expression in tissue culture. One mutant, d109, does not express any of the five IE proteins, is completely nontoxic, and establishes a long term relationship with the cell. Gene expression from the persisting genomes is repressed, but can be induced by the addition of ICP0. Therefore, some of the events occurring in d109-infected tissue culture cells are similar to those that may occur with latent genomes in vivo. We propose that the activity of ICP0 results in changes to the cellular pathways involved in repression and derepression of gene expression. Two pathways will be investigated; the histone acetylation pathway and the ubiquitin/proteasome pathway. Data is provided that the action of ICP0 resembles the action of the histone deacetylase inhibitor, trichostatin A, with respect to induction of repressed genomes, effects on cell cycle, and the induction of cellular genes. Unlike other latency model systems, the proposed system is very amenable to quantitative biochemical and molecular characterization. The proposed specific aims are to; i. Examine gene expression and the physical state of persisting viral genomes. ii) Determine how ICP0 alters this state relative to inhibitors of the acetylation and proteasome pathways. iii) Determine the effects of ICP0 on host cell gene expression and histone modification, and compare these to the effects of inhibitors of the acetylation and proteasome pathways. and iv) Determine if changes in the acetylation and proteasome pathways affect HSV infection in a similar way to ICP0. The results of this study will provide insight into how ICP0 affects cells, and how the HSV genome can be repressed and maintained in a latent state, and subsequently reactivated.