Role of HSV Induced RNA Degradation in Pathogenesis

项目摘要/摘要 单纯疱疹病毒(HSV)角膜炎是发达国家非外伤性失明的主要原因， 美国有40多万个病例，每年大约有50,000个新病例和复发病例。单纯疱疹病毒 引起各种眼部疾病，包括自限性树突状上皮角膜炎、结膜炎和 眼缘炎，到严重的坏死性间质角膜炎。此外，单纯疱疹病毒会引起唇疱疹、生殖器溃疡，而且是一种 病毒性脑炎的主要原因。单纯疱疹病毒的生命周期由粘膜部位的裂解阶段组成，在此期间 所有的病毒基因都是表达的，在神经元中有一个潜伏期，在这个潜伏期，基因的表达非常 有限的。潜伏期是HSV周期性重新激活的永久性蓄水池，导致严重的 粘膜皮肤损伤。重新激活非常频繁，会导致病毒脱落。延迟呈现HSV 尽管有有效的抗病毒药物，但仍无法治愈，也没有有效的HSV疫苗存在。更好 治疗和了解疱疹眼病是NEI角膜疾病计划的明确目标。 嗜神经性疱疹病毒迅速切断受感染细胞的蛋白质合成。单纯疱疹病毒的主效基因 负责这种关闭的是病毒粒子宿主关闭蛋白或VHS。VHS是一种核糖核酸酶，诱导迅速 宿主mRNAs的不稳定。所有嗜神经性疱疹病毒都有VHS的同源物，尽管其他类别的 人类疱疹病毒和其他重要病原体(如SARS)破坏宿主mRNA的稳定。此属性是一个 临界毒力决定因素。我们发现VHS活性在感染和损伤中起着重要作用。 在眼部，在眼周疾病的发展中，在潜伏期的建立中。VHS活动改变 先天免疫反应的大小和我们确定的VHS内的功能区域，表征了 对其在被膜中的活动至关重要的区域，并表明VHS在神经系统中活动。此外 VHS缺陷病毒是唯一有效的治疗性疫苗(美国专利号5698431)。 我们目前的工作假设是，VHS决定了体内感染的结局，因为它能够改变 具有先天免疫功能，促进复制。先天免疫是决定病毒结局的关键。 在预防动物模型中的全身性和致命性感染方面也是如此。最重要的是，人类 缺乏干扰素介导的抗病毒反应极易感染HSV。更好地理解先天 因此，需要对病毒感染作出反应。此外，对VHS功能的更好定义将定义 针对单纯疱疹病毒疾病的治疗干预目标，以及协助设计单纯疱疹病毒疫苗。 此外，越来越多的证据表明，诱导宿主的mrna降解也是一种致病机制。 其他人类病原体的决定因素。病毒诱导的RNA不稳定的特定抑制剂可能 因此，作为广谱抗病毒药物具有价值。因此，这项工作具有广泛的兴趣和应用。

Project Summary/Abstract Herpes simplex virus (HSV) keratitis is a leading cause of non-traumatic blindness in developed countries, with more than 400,000 cases in the USA, with approximately 50,000 new and recurring cases per year. HSV causes a variety of ocular diseases ranging from self-limiting dendritic epithelial keratitis, conjunctivitis, and blepharitis, to severe necrotizing stromal keratitis. In addition, HSV causes cold sores, genital sores, and is a leading cause of viral encephalitis. The HSV life cycle consists of a lytic phase at mucosal sites during which all virus genes are expressed, and a latent phase in neurons, during which gene expression is extremely limited. Latency is a permanent reservoir from which HSV periodically reactivates to cause severe mucocutaneous damage. Reactivation is very frequent and results in viral shedding. Latency renders HSV resistant to cure despite the availability of effective antiviral drugs, and no effective HSV vaccine exists. Better treatment and understanding of herpetic ocular disease is a stated goal of the NEI Corneal Diseases Program. Neurotropic herpesviruses rapidly shut off protein synthesis in infected cells. For HSV the major gene responsible for this shutoff is the virion host shutoff protein or vhs. Vhs is an RNAse, inducing rapid destabilization of host mRNAs. All neurotropic herpesviruses have a homolog of vhs although other classes of human herpesviruses and other important pathogens (e.g. SARS) destabilize host mRNA. This property is a critical virulence determinant. We showed that vhs activity plays an essential role in the infection and damage of the eye, in the development of periocular disease, and in the establishment of latency. Vhs activity alters the magnitude of the innate immune response and we identified functional domains within vhs, characterized a domain critical for its activity in the tegument, and shown that vhs is active in the nervous system. In addition viruses deficient in vhs are uniquely effective therapeutic vaccines (US Patent #5698431). Our current working hypothesis is that vhs determines the outcome of infection in vivo due to its ability to alter innate immune function and promote replication. Innate immunity is pivotal in determining the outcome of virus infection, and in the prevention of systemic and fatal infections in animal models. Most importantly, humans lacking interferon-mediated antiviral responses are highly susceptible to HSV. A better understanding of innate responses to virus infection is therefore needed. In addition, a better definition of vhs functions will define targets for therapeutic intervention against HSV diseases, as well as aid in design of HSV vaccines. Furthermore, there is emerging evidence that induction of host mRNA degradation is also a pathogenesis determinant for other human pathogens. Specific inhibitors of virus-induced RNA destabilization might therefore be of value as broad-spectrum antivirals. This work is therefore of broad interest and application.