Ocular HSV: Mechanism of virus reactivation

项目摘要 原发性眼部HSV-1感染后，病毒在眼部复制，并在眼部建立潜伏期。 三叉神经节（TG）。在潜伏感染的个体中，病毒偶尔会重新激活并返回 引起复发性疾病的眼睛。潜伏期的再激活是眼部疾病的主要原因。但 这一过程的机制尚未明确，目前尚不清楚是否重新激活 反映延迟机制或中断延迟的独立机制中的故障。公认的情况是 HSV-1潜伏相关转录物（LAT）的持续表达是潜伏期的特征， 这与抑制细胞凋亡和调节T细胞对感染的感觉神经元的反应有关。 神经元最近，我们发现在感染LAT（-）病毒的小鼠的TG中，HSV-1受体的水平， HVEM，而不是其他HSV-1受体显著下调。此外，HSV-1潜伏期和 与野生型小鼠相比，HVEM-/-小鼠的再激活显著减少。值得注意的是， 在上调HVEM中的功能，其定位于两种最近描述的小的非编码LAT RNA（sncRNA 1和 2），因为HVEM在用表达小的非- 编码RNA。与此同时，我们发现病毒糖蛋白gD能够结合HVEM并触发其 通过NF-κB的信号传导，在潜伏感染的TG中以低水平表达。总的来说，我们的初步数据 提供令人信服的证据支持LAT可以增强潜伏期再激活和T细胞 通过上调HVEM，这反过来又促进HSV-1的再活化，可能是通过促进HSV-1的再活化， gD与HVEM的结合。虽然表达杆状病毒凋亡抑制蛋白基因的LAT（-）病毒 （cpIAP）与野生型LAT（+）病毒具有相似的潜伏期水平，但该重组病毒不增加HVEM 水平表明，这种再激活机制不会通过调节反应性来促进再激活 到凋亡。相反，这种机制似乎干扰LAT促进免疫逃避的能力。 我们建议使用工程重组病毒的体内分析来检验这一假设，以：（1）检验 HSV-1 gD与HVEM的结合是否是潜伏感染的TG中有效再活化所必需的 小鼠;和（2）测试LAT sncRNA是否通过结合HVEM启动子上调HVEM。 验证这一假设模型将确定以前未描述的机制，有助于HSV-1 并将为鉴定分子靶点和病毒免疫逃避提供框架 可以利用这种反应来更好地管理潜伏的HSV感染。 临床意义及

Project Summary Following primary ocular HSV-1 infection, the virus replicates in the eye and establishes latency in the trigeminal ganglia (TG). In a latently infected individual, the virus can occasionally reactivate and travel back to the eye causing recurrent disease. Reactivation from latency is the major cause of eye disease. However, the mechanisms underlying this process are not well defined, and currently it is not clear whether reactivation reflects a failure in latency mechanisms or independent mechanisms that break latency. It is well established that the continued expression of the HSV-1 Latency Associated Transcript (LAT) is a characteristic of latency, and this is associated with suppression of apoptosis and regulation of T cell responses to the infected sensory neurons. Recently, we found that in the TG of mice infected with LAT(-) virus, the levels of the HSV-1 receptor, HVEM, but not other HSV-1 receptors was significantly down-regulated. Furthermore, HSV-1 latency and reactivation were reduced significantly in HVEM-/- mice as compared to wild-type mice. Notably, the LAT function in upregulating HVEM mapped to two recently described small non-coding LAT RNAs (sncRNA1 and 2), since HVEM was upregulated following transient transfection with plasmids expressing either small non- coding RNA. In parallel, we have found that viral glycoprotein gD, capable of binding HVEM and triggering its signaling through NF-κB, is expressed at low levels in latently infected TG. Collectively, our preliminary data provide compelling evidence supporting the hypothesis that LAT can enhance latency-reactivation and T-cell exhaustion by upregulating HVEM, which in turn promotes HSV-1 reactivation, possibly by facilitating the binding of gD to HVEM. Although the LAT(-) virus expressing baculovirus inhibitor of apoptosis protein gene (cpIAP) had similar levels of latency as wild-type LAT(+) virus, this recombinant virus did not increase HVEM levels suggesting that this reactivation mechanism does not promote reactivation by regulating responsiveness to apoptosis. Rather, this mechanism appears to interfere with the ability of LAT to promote immune evasion. We propose to test this hypothesis using in vivo analyses of engineered recombinant viruses to: (1) Test whether binding of HSV-1 gD to HVEM is required for efficient reactivation in TG of latently infected mice; and (2) Test whether the LAT sncRNAs upregulate HVEM by binding to the HVEM promoter. Validation of this hypothetical model will identify previously undescribed mechanisms that contribute to HSV-1 reactivation and will provide the framework for identification of molecular targets and viral immune evasion response that could be exploited to better manage latent HSV infection. CLINICAL SIGNIFICANCE AND