VZV in the enteric nervous system: pathogenesis and consequences

描述（由申请人提供）：肠神经系统（ENS）可以在没有来自大脑或脊髓的输入的情况下控制肠道的行为。功能正常的ENS对生命至关重要，当异常时，会引起不适，并可能导致胃肠道运动、分泌和炎症疾病的病理生理学或严重程度。我们最近发现，水痘带状疱疹病毒（VZV）建立潜伏期内的人肠神经元在大多数人谁经历了自然水痘或接受水痘疫苗。此外，VZV与免疫功能低下个体中致命性假性梗阻的发生有关。VZV进入ENS的途径，以及其在肠神经元中再激活的频率或后果（“肠带状疱疹”）以前都没有被探索过。目前的提议旨在测试以下假设：内脏传入神经中的转运将VZV传导至ENS，无细胞病毒粒子在肠神经元中建立潜伏期，以及非结构性VZV ORF 61蛋白必须在神经元中表达以使VZV能够表现出裂解性感染或从潜伏期重新激活。虽然VZV显示出对人类细胞的明显偏好，但我们已经开发出允许VZV感染ENS的动物模型，以在体外和体内进行研究。根据条件，VZV重演从豚鼠或小鼠分离的肠神经元中的潜伏性、溶解性和再活化感染，并且当引入肠时，VZV在豚鼠ENS中原位建立潜伏期。该提案有3个具体目标：（1）VZV能否从皮肤到感觉神经纤维中的ENS旅行？初步研究已经确定了背路神经节中的神经元，它们可以投射到皮肤和肠道。我们将确定当VZV被引入皮肤时是否在ENS中建立潜伏感染，以及VZV感染的神经末梢是否释放感染性无细胞VZV，其穿过突触间隙将潜伏感染转移到靶神经元。(2)病毒血症是否能引起肠神经元的潜伏性VZV感染？我们将确定VZV感染的T淋巴细胞是否释放感染性无细胞VZV，以及它们是否可以直接在肠神经元中建立潜伏期或间接通过粘膜上皮或皮肤的感染。初步研究表明，VZV DNA存在于豚鼠肠神经元静脉注射VZV感染的外周血单核细胞。(3)VZV ORF61蛋白表达是否是肠神经元溶解性感染的表现所必需的？我们将研究缺乏ORF61的VZV突变体建立肠神经元裂解性感染或从潜伏期重新激活的能力。肠神经元中VZV的意外再激活可能导致胃肠道疾病（如肠易激综合征、炎症性肠病、特发性胃轻瘫和慢性假性肠梗阻）的发病机制，这一可能性增强了理解ENS VZV感染的意义。 公共卫生相关性：肠道包含一个庞大而复杂的神经细胞网络，称为肠神经系统（ENS），它能够在没有来自大脑或脊髓的输入的情况下控制肠道的行为。ENS是许多扰乱ENS功能的疾病的基础，例如肠易激综合征、炎症性肠病、特发性胃轻瘫和慢性假性肠梗阻，目前尚不清楚。我们最近发现，水痘带状疱疹病毒（VZV）建立潜伏期内的神经细胞的人ENS。无论是原因，也没有这种现象的后果以前被探索，因为潜伏的VZV在肠神经细胞是未知的发生。目前的建议旨在确定VZV如何进入ENS，我们将利用肠神经细胞来测试以下假设：只有无细胞颗粒形式的VZV能够在肠或其他神经细胞中建立潜伏期，以及在感染细胞中产生但不掺入病毒颗粒的病毒蛋白（ORF 61 p）是VZV引起感染所必需的，该感染产生更多的病毒并杀死被感染的细胞（裂解性感染）或从神经细胞中的潜伏期重新激活。

DESCRIPTION (provided by applicant): The enteric nervous system (ENS) can control the behavior of the bowel without input from brain or spinal cord. A functioning ENS is essential for life and, when abnormal, causes discomfort and may contribute to the pathophysiology or severity of disorders of gastrointestinal motility, secretion, and inflammation. We have recently discovered that varicella zoster virus (VZV) establishes latency within human enteric neurons in most individuals who have experienced natural varicella or received varicella vaccine. VZV, moreover, has been linked to the occurrence of lethal pseudoobstruction in immunocompromised individuals. Neither the route by which VZV gains access to the ENS, nor the frequency or consequences of its reactivation in enteric neurons ("enteric zoster") has previously been explored. The current proposal is designed to test the hypotheses that transport in visceral afferent nerves conducts VZV to the ENS, that cell- free virions establish latency in enteric neurons, and that the non-structural VZV ORF61 protein must be expressed in neurons to enable VZV to manifest lytic infection or to reactivate from latency. Although VZV displays a marked preference for human cells, we have developed animal models that permit VZV infection of the ENS to be studied in vitro and in vivo. Depending on conditions, VZV recapitulates latent, lytic, and reactivating infection in enteric neurons isolated from guinea pigs or mice and, when introduced to the bowel, VZV establishes latency in the guinea pig ENS in situ. The proposal has 3 specific aims: (1) Can VZV travel from the skin to the ENS in sensory nerve fibers? Preliminary studies have identified neurons in dorsal route ganglia that project both to skin and gut. We will determine whether latent infection is established in the ENS when VZV is introduced to the skin and whether VZV-infected nerve terminals release infectious cell-free VZV that crosses synaptic gaps to transfer latent infection to target neurons. (2) Can a viremia establish latent VZV infection of enteric neurons? We will determine whether VZV-infected T lymphocytes release infectious cell-free VZV and whether they can establish latency directly in enteric neurons or indirectly via infections of the mucosal epithelium or skin. Preliminary studies have shown that VZV DNA is present in guinea pig enteric neurons following the iv injection of VZV-infected peripheral blood mononuclear cells. (3) Is VZV ORF61 protein expression necessary for the manifestation of lytic infection in enteric neurons? We will study the ability of a VZV mutant that lacks ORF61 to establish lytic infection of enteric neurons or reactivate from latency. The significance of understanding VZV infection of the ENS is enhanced by the possibility that unsuspected reactivation of VZV in enteric neurons might contribute to the pathogenesis of GI disorders such as irritable bowel syndrome, inflammatory bowel disease, idiopathic gastroparesis, and chronic intestinal pseudoobstruction. PUBLIC HEALTH RELEVANCE: The gut contains a large and complex network of nerve cells, known as the enteric nervous system (ENS), which is able to control the behavior of the bowel without input from the brain or spinal cord. The ENS contributes to the underlying basis of a number of disorders that disturb the functioning of ENS, such as irritable bowel syndrome, inflammatory bowel disease, idiopathic gastroparesis, and chronic intestinal pseudoobstruction are currently not understood. We have recently discovered that varicella zoster virus (VZV) establishes latency within nerve cells of the human ENS. Neither the cause nor the consequences of this phenomenon have previously been explored because latent VZV in enteric nerve cells was not known to occur. The current proposal is designed to determine how VZV gains access to the ENS and we will utilize enteric nerve cells to test the hypotheses that only the cell-free particle form of VZV is able to establish of latency in enteric or other nerve cells and that a viral protein that is produced in infected cells but which is not incorporated into viral particles (ORF61p) is required for VZV to give rise to an infection that produces more virus and kills infected cells (lytic infection) or to reactivate from latency in nerve cells.