Molecular Analysis of HSV-1 Reactivation from Latency

描述（由申请人提供）：单纯疱疹病毒（HSV）感染在全球人口中持续呈流行病水平，造成严重的健康后果。干预HSV从潜伏状态重新激活是控制这一流行病努力的关键组成部分。所提出的研究的长期目标是获得控制从潜伏期转录到裂解期转录转变的分子机制的知识，用于合理设计干预策略。人们普遍认为，在初次感染期间启动病毒裂解级联反应的病毒/宿主细胞相互作用不同于那些在潜伏病毒基因组中启动病毒裂解级联反应的相互作用。这一观点是基于这样一个事实，即α基因转导因子（VP16）作为蛋白质与病毒粒子一起被带入，直到裂解周期的后期才作为蛋白质被纳入病毒粒子中。因此，这个重要的病毒反激活因子被认为在潜伏期间以及在潜伏病毒基因组的转录激活期间不存在。这表明除了明确定义的VP16/Octl/HCF/taatgarat复合体外，有必要确定病毒/宿主转录激活界面。尽管IE基因ICP0被认为是可能“取代”VP16启动裂解周期的候选基因，并且对ICP0功能的研究已经揭示了该蛋白在修饰宿主细胞环境中的作用，但仍然没有证据表明ICP0启动进入裂解周期。我们已经获得了令人信服的表型和生化数据，表明VP16在重新激活的启动中起着关键作用。这一关键观察结果要求集中检查病毒IE基因转录从潜伏期上调的机制。以下具体目标将引导我们通过系统的解剖(1)VP16在再激活启动过程中的作用；(2) VP16启动子元件在应力驱动下的上调；(3)病毒基因组结构在转录沉默和启动再激活中的调控作用。发展和改进方法，以方便对神经节中单个神经元发生的事件进行常规检查和量化，是我们取得进展的基础。这些分析工具将与病毒基因组的精确工程和染色质结构分析的进展一起用于这些研究。

DESCRIPTION (provided by applicant): Herpes simplex virus (HSV) infection continues at epidemic levels in the global human population with serious health consequences. Intervention of the reactivation of HSV from the latent state is a critical component of efforts to control this epidemic. The long-term goal of the proposed research is to acquire knowledge of the molecular mechanisms controlling the transition from latent to lytic phase transcription for use in the rational design of intervention strategies. It is widely accepted that the viral/host cell interactions initiating the viral lytic cascade during primary infection are distinct from those initiating the lytic cascade from the latent viral genome. This notion is rooted in the fact that the alpha gene transinducing factor (VP16) is brought in with the virion as a protein and not made until late in the lytic cycle when it is incorporated as protein into the virion. Thus this important viral transactivator is thought to be absent during latency as well as during activation of transcription from the latent viral genome. This presents the necessity to identify a viral/host transcriptional activation interface other than the well-defined VP16/Octl/HCF/taatgarat complex. Although the IE gene ICP0 has been viewed as the likely candidate to "replace" VP16 in initiating the lytic cycle, and studies of ICP0 function have revealed much about the role of this protein in modifying the host cell environment, there remains no evidence that ICP0 initiates entry into the lytic cycle. We have generated compelling data, both phenotypic and biochemical that marks VP16 as a critical player in the initiation of reactivation. This key observation calls for a focused examination of the mechanism of upregulation of viral IE gene transcription from latency. The following specific aims will guide us through a systematic dissection of (1) the role of VP16 during the initiation of reactivation; (2) the VP16 promoter elements required for its stress driven upregulation; and (3) the role of viral genome structure in the regulation of transcriptional silencing and initiation of reactivation. The development and refinement of methodologies to facilitate routine examination and quantification of the events occurring in individual neurons in the ganglia have been fundamental to our progress. These analytical tools together with precision engineering of the viral genome and advances in the analysis of chromatin structure will be utilized for these studies.