Role of HSV Induced RNA Degradation in Pathogenesis

描述(申请人提供)：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，在美国有40多万例，每年约有50,000例新发和复发病例。单纯疱疹病毒可引起多种眼部疾病，从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，并且是病毒性脑炎的主要原因。HSV的生命周期包括粘膜部位的裂解期和神经元的潜伏期，在此期间所有病毒基因都得到了表达，在此期间，基因的表达极其有限。潜伏期是一个永久性的蓄水池，HSV从这里周期性地重新激活，导致严重的粘膜皮肤损害。重新激活非常频繁，会导致病毒脱落。潜伏期使HSV无法治愈，尽管有有效的抗病毒药物可用，而且没有有效的HSV疫苗存在。更好地治疗和了解疱疹眼病是NEI角膜疾病计划的一个明确目标。嗜神经性疱疹病毒迅速切断受感染细胞的蛋白质合成。对于单纯疱疹病毒来说，导致这种关闭的主要基因是病毒粒子宿主关闭蛋白或VHS。VHS是一种核糖核酸酶，导致宿主mRNAs的快速失稳。所有嗜神经性疱疹病毒都有VHS的同源物，尽管其他类型的人类疱疹病毒和其他重要的病原体(如SARS)会破坏宿主mRNA的稳定。这一特性是一个关键的毒力决定因素。我们发现VHS活性在眼睛的感染和损伤、眼周疾病的发展和潜伏期的建立中起着重要的作用。VHS的活性改变了先天免疫反应的大小，我们确定了VHS内的功能区域，描述了被膜中对其活动至关重要的区域，并表明VHS在神经系统中是活跃的。此外，缺乏VHS的病毒是唯一有效的治疗性疫苗(美国专利5698431号)。我们目前的工作假设是VHS决定了体内感染的结果，因为它能够改变先天免疫功能并促进复制。在动物模型中，先天免疫在决定病毒感染的结果以及预防全身性和致命性感染方面起着关键作用。最重要的是，缺乏干扰素介导的抗病毒反应的人非常容易感染HSV。因此，需要更好地了解对病毒感染的先天反应。此外，对VHS功能的更好定义将确定针对HSV疾病的治疗干预目标，以及有助于HSV疫苗的设计。此外，越来越多的证据表明，宿主mRNA降解的诱导也是其他人类病原体的致病决定因素。因此，病毒诱导的RNA不稳定的特定抑制剂可能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。公共卫生相关性：单纯疱疹病毒(HSV)是发达国家非外伤性失明的主要原因，也是唇疱疮、生殖器溃疡和脑炎的病原体。我们工作的目标是在小鼠眼睛模型中识别参与疾病发病机制的宿主和病毒基因。这项工作的成功结果可能会为疱疹感染的新疗法和疫苗铺平道路。

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: Herpes simplex virus (HSV) is a leading cause of non-traumatic blindness in developed countries as well as the causative agent of cold sores, genital sores, and encephalitis. The goal of our work is to identify host and viral genes that are involved in the pathogenesis of disease in a mouse ocular model. The successful outcome of this work will likely pave the way for new treatments and vaccines for therapy of herpes infections.