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激活立即早期（IE）转录， 由输入病毒体提供。 IE蛋白然后起作用以诱导和 调节HSV基因组其余部分的表达。 期间 潜伏期，病毒裂解基因表达不发生，基因组 作为包装在染色质中的附加体元件持续存在。重新激活 潜伏期可能涉及基因组的激活， VP16。 一种IE蛋白，ICP0，已经被证明参与了 在几个模型系统中从潜伏期重新激活的过程。ICPO已 还显示促进裂解性病毒基因表达。 而其 作用机制尚不清楚，但已显示与 泛素蛋白酶 使用在免疫缺陷病毒的亚群中缺陷的突变体， IE蛋白提供了检测病毒基因表达的手段， 在组织中不存在裂解基因表达的情况下的基因组持久性 文化 一个突变体d109不表达五个IE基因中的任何一个。 蛋白质，是完全无毒的，并建立一个长期的 与细胞的关系。 来自持续基因组的基因表达 被抑制，但可以通过加入ICP0诱导。因此，我们认为， 在D109感染的组织培养细胞中发生的一些事件是 类似于体内潜在基因组可能发生的情况。 我们提出 ICP0的活性导致细胞通路的变化， 参与基因表达的抑制和去抑制。 两 途径将被调查;组蛋白乙酰化途径和 泛素/蛋白酶体途径。 提供的数据表明， 类似于组蛋白去乙酰化酶抑制剂的作用 A，关于阻遏基因组的诱导，对细胞的影响， 周期，以及细胞基因的诱导。 与其他延迟模型不同 系统，建议的系统是非常适合定量 生物化学和分子表征。 拟议的具体目标 是; i.检查基因表达和持续存在的物理状态 病毒基因组ii）确定ICP0如何相对于 乙酰化和蛋白酶体途径的抑制剂。iii）确定 ICP0对宿主细胞基因表达和组蛋白的影响 修饰，并将这些与抑制剂的作用进行比较。 乙酰化和蛋白酶体途径。（四）确定是否发生变化， 乙酰化和蛋白酶体途径影响HSV感染， 到ICP0。 这项研究的结果将提供洞察如何 ICP0影响细胞，以及HSV基因组如何被抑制， 保持在潜伏状态，随后被重新激活。

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.