Varicella zoster virus-Induced Pain in a Rat Model of Post-Herpetic Neuralgia

描述(申请人提供)：带状疱疹后遗神经痛(PHN)是一种常见且极度痛苦的并发症，使人虚弱、顽固、持久且难以治疗。PHN随着年龄的增长而急剧增加，因此是一种老年人的疾病，可能会严重降低生活质量。鉴于我们社会的老龄化，PHN将成为一个更加紧迫的公共卫生问题。当人类疱疹病毒水痘-带状疱疹病毒(VZV)从水痘期间宿主感觉神经元建立的潜伏状态重新激活时，带状疱疹和PHN就会发生。虽然病毒复制导致神经损伤和炎症引发疼痛，但VZV引起持续性疼痛的机制尚不清楚。本项目针对FOA PA-07-282，并将集中在一种新的临床相关的VZV诱导的疼痛模型上，在该模型中，将人VZV注射到大鼠后足后，会出现长时间的痛敏和超敏。这一建议的基本假设是，通过使用这个新的大鼠模型，我们将能够更好地理解VZV如何与初级传入系统相互作用来诱导疼痛，并测试治疗VZV引起的疼痛的新的基因治疗方法。在具体目标1中，我们将通过使用一组全面的抗体来表征VZV诱导伤害性反应之前、期间和之后背根神经节(DRG)感觉神经元中病毒和疼痛标记蛋白的表达，从而研究VZV感染大鼠的生物学特性。我们将确定哪些VZV蛋白在每个阶段在DRG中表达，并解决病毒基因表达模式是否与疼痛反应和疼痛恢复相关。我们还将确定表达VZV抗原的神经元的类型，并确定它们是否在DRG和脊髓显示神经病理性和/或炎症性疼痛的标志物上调。这项工作将建立模型中潜在的VZV生物学，以及疼痛反应是与人类VZV裂解感染或VZV潜伏期相似的感染过程的结果。在特定的目标2中，我们将通过测试以下各项的能力来询问哪些VZV蛋白是诱导疼痛所必需的：1)各种突变的VZV重组体，每个VZV重组体都改变了特定的调节病毒基因；2)各种HSV载体，每个构建成表达单一的VZV调节基因，以诱导伤害性感受。这可能会识别特定的VZV蛋白，以便在开发止痛策略时进一步靶向，并可能导致改进的疫苗，而不是诱导PHN的能力。第三个具体目标将通过验证HSV载体介导的痛觉调节剂传递可以减少VZV引起的痛觉过敏和痛觉过敏的假说来探索新的治疗途径。我们将研究使用HSV载体表达脑啡肽原、GAD、甘氨酸受体和抗炎蛋白来治疗VZV诱导的超敏反应，所有这些都已被证明在其他系统中可以减轻疼痛。总之，对这一模型的探索可能会导致对细胞变化的理解，这些变化可能是VZV产生疼痛的基础，这不仅将增加对病原体：VZV感染中宿主相互作用的了解，而且可能有助于为治疗干预开发新的分子靶点。本项目研究由疱疹病毒水痘带状疱疹病毒引起的一种新的疼痛模型，该模型反映了一种常见的、高度衰弱的人类老年人疾病--带状疱疹后遗神经痛(PHN)。对该模型的检查可能会为止痛策略的开发确定新的靶点，并可能导致识别出无法引起疼痛的改进的候选疫苗。该项目还可能确定使用基因疗法来缓解PHN的新方法。

DESCRIPTION (provided by applicant): Post-Herpetic Neuralgia (PHN) is a common and exceedingly painful complication of herpes zoster that is debilitating, intractable, long-lasting and difficult to treat. PHN increases dramatically with age, and is thus a disease of the elderly which may profoundly reduce the quality of life. Given the aging nature of our society, PHN will become an even more pressing public health concern. Zoster and PHN occur when the human herpesvirus, varicella-zoster virus (VZV), reactivates from a latent state that was established in the host sensory neurons during chickenpox. While viral replication induces nerve damage and inflammation to initiate pain, the mechanisms by which VZV causes persistent pain are not well understood. This project is directed to FOA PA-07-282, and will center on a new clinically relevant model of VZV-induced pain in which prolonged hyperalgesia and allodynia occur following injection of human VZV into the rat hindpaw. The overlying hypothesis of this proposal is that by using this new rat model we will be able to better comprehend how VZV interacts with the primary afferent system to induce pain and test novel gene therapy approaches to treat VZV induced pain. In Specific Aim 1, we will examine the biology of VZV infection in the rat by characterizing viral and pain marker protein expression in the dorsal root ganglion (DRG) sensory neurons before, during and after VZV-induced nociception, using a comprehensive panel of antibodies. We will determine which VZV proteins are expressed in the DRG at each stage and address if viral gene expression patterns correlate with the pain response and recovery from it. We will also identify types of neurons expressing VZV antigens and determine if they display an upregulation of markers of neuropathic and/or inflammatory pain at both the DRG and the spinal cord. This work will establish the underlying VZV biology in the model and whether the pain response is a result of an infectious process with similarities to human VZV lytic infections or to VZV latency. In Specific aim 2, we will ask what specific VZV proteins are necessary to induce pain by testing the ability of: 1) various mutant VZV recombinants, each altered in a specific regulatory viral gene, and 2) various HSV vectors, each constructed to express a single VZV regulatory gene, to induce nociception. This may identify specific VZV proteins for further targeting in developing anti-pain strategies, and may lead to improved vaccines without the ability to induce PHN. The third specific aim will explore new avenues of treatment by testing the hypothesis that HSV vector-mediated delivery of modulators of pain can reduce the allodyna and hyperalgesia induced by VZV. We will investigate the use of HSV vectors expressing pro-enkephalin, GAD, the glycine receptor, and anti inflammatory proteins to treat VZV-induced hypersensitivity in the model, all of which have been shown to reduce pain in other systems. Together, exploration of this model may lead to an understanding of cellular changes that may underlie the generation of pain by VZV that will not only add to knowledge of pathogen:host interactions in VZV infection, but may help in developing new molecular targets for therapeutic intervention. This project studies a new model of pain induced by the herpesvirus varicella zoster virus that is reflective of a common and highly debilitating human disease of the elderly, post herpetic neuralgia (PHN). The examination of the model may identify new targets for the development of anti-pain strategies, and may lead to the identification of improved vaccine candidates that are unable to induce pain. The project may also identify new methods to alleviate PHN using gene therapy approaches.