Investigation of herpes simplex virus -1 neurotropism in SCID DRG xenografts

描述（由申请方提供）：单纯疱疹病毒-1（HSV-1）是一种人α疱疹病毒，在原发性感染后在外周神经节中建立终身潜伏感染。HSV-1感染通常是良性的，尽管其神经毒力和神经侵入性的能力是HSV-1可在人类，特别是新生儿和免疫功能低下的宿主中引起有害疾病的主要机制。我们的总体目标是建立一个模型，检查HSV-1在人体感觉神经节在体内的神经发病机制。我们将评估HSV-1感染的人背根神经节（DRG）异种移植物在小鼠严重联合免疫缺陷（SCID），利用我们创建的系统，研究水痘-带状疱疹病毒（VZV）的神经发病机制。HSV-1感染的生物学类似于VZV，因为HSV-1和VZV在原发感染后均在感觉神经节内建立潜伏期。在SCIDhu DRG模型中对VZV的研究提供了第一次机会来检查人α疱疹病毒在体内包含人DRG的细胞内的复制。DRG异种移植模型有可能在实验系统中揭示体内天然人类宿主组织微环境中HSV-1神经发病机制的特征，这将大大增加啮齿动物模型的观察结果。实验将针对三个具体目标：（1）我们将确定在SCID小鼠中接种HSV-1的人DRG异种移植物后的事件过程，鉴定DRG内哪些细胞类型允许HSV-1基因表达，神经元和/或卫星细胞是否被有效感染，以及HSV-1是否经历了我们在VZV中观察到的在人类神经元中持续存在的转变模式，（2）我们将通过评价重组HSV-1毒株来研究HSV-1基因功能，特别是我们将研究在初始感染期间对HSV-1胸苷激酶（TK）的需求和在DRG中的持续性，以及gD突变体的病毒进入能力;（3）如果显示HSV-1在DRG异种移植物中建立持久性，我们将评估该模型是否可用于研究HSV-1的再激活，通过阻断潜伏感染的DRG异种移植物，并使用触发神经细胞信号传导途径和增加HSV-1的药物进行治疗。1在啮齿动物模型中的再活化。这项工作旨在证明在SCID小鼠中使用DRG异种移植物的可行性，以探索HSV-1在体内感觉神经节组织微环境中分化的人类感觉神经元和非神经元细胞中神经发病的分子机制。除了关于基本病毒-宿主相互作用的新见解之外，这种模型对于研究抗病毒药物和减毒HSV-1活疫苗候选物以治疗或预防由这种常见病毒引起的人类疾病具有潜在价值。公共卫生相关性：单纯疱疹病毒1型（HSV-1）引起口腔和生殖器病变和脑炎。这些感染仍然是美国重要的公共卫生问题。HSV-1的严重并发症可能发生在健康人和那些患有损害免疫系统的疾病的人身上。我们的目标是开发一个模型来研究HSV-1如何感染人类神经细胞，这将对开发新药和疫苗具有潜在价值。

DESCRIPTION (provided by applicant): Herpes simplex virus-1 (HSV-1) is human alphaherpesvirus that establishes a lifelong latent infection in peripheral nerve ganglia following primary infection. HSV-1 infections are generally benign, although its capacity for neurovirulence and neuroinvasiveness are the primary mechanisms through which HSV-1 can cause harmful disease in humans, especially in neonates and immunocompromised hosts. Our overall objective is to develop a model for examining HSV-1 neuropathogenesis in human sensory ganglia in vivo. We will evaluate HSV-1 infection of human dorsal root ganglion (DRG) xenografts in mice with severe combined immunodeficiency (SCID), exploiting the system that we created to investigate varicella- zoster virus (VZV) neuropathogenesis. The biology of HSV-1 infection is similar to VZV in that both HSV-1 and VZV establish latency within sensory ganglia following primary infection. Studies of VZV in the SCIDhu DRG model have provided the first opportunity to examine replication of a human alphaherpesvirus within cells that comprise human DRG in vivo. The DRG xenograft model has the potential to reveal characteristics of HSV-1 neuropathogenesis in the natural human host tissue microenvironment in vivo in an experimental system that will add substantially to observations from rodent models. Experiments will address three specific aims: (1) we will define the course of events that follows HSV-1 inoculation of human DRG xenografts in SCID mice, identifying what cell types within DRG are permissive for HSV-1 gene expression, whether neurons and/or satellite cells become productively infected and whether HSV-1 undergoes the pattern of transition to persistence in human neurons that we have observed in VZV-infected DRG xenografts; (2) we will investigate HSV-1 gene functions through the evaluation of recombinant HSV-1 strains, in particular we will examine the requirement for HSV-1 thymidine kinase (TK) during initial infection and persistence in DRG, and gD mutants for their capacity for viral entry; (3) if HSV-1 is shown to establish persistence in DRG xenografts, we will assess whether this model can be used to study HSV-1 reactivation by explanting latently-infected DRG xenografts and treating with agents that trigger neural cell signaling pathways and increase HSV-1 reactivation in rodent models. This work is intended to demonstrate the feasibility of using DRG xenografts in SCID mice to explore the molecular mechanisms of HSV-1 neuropathogenesis in differentiated human sensory neurons and non-neuronal cells within their sensory ganglia tissue microenvironment in vivo. In addition to new insights about basic virus-host interactions, such a model has potential value for studying antiviral drugs and live attenuated HSV-1 vaccine candidates to treat or prevent human disease caused by this common virus. PUBLIC HEALTH RELEVANCE: Herpes Simplex Virus 1 (HSV-1) causes oral and genital lesions and encephalitis. These infections remain an important public health problem in the United States. Serious complications from HSV-1 can occur in healthy people and in those who have diseases that impair their immune systems. Our goal is to develop a model to study how HSV-1 infects human nerve cells that will have potential value for developing new drugs and vaccines.