Role of HSV Induced RNA Degradation in Pathogenesis

描述（由申请人提供）：单纯疱疹病毒（HSV）角膜炎是发达国家非创伤性失明的主要原因，在美国有超过40万例，每年约有5万例新发和复发病例。单纯疱疹病毒引起多种眼部疾病，从自限性树突状上皮性角膜炎、结膜炎和睑缘炎到严重的坏死性间质角膜炎。此外，单纯疱疹病毒引起唇疱疹、生殖器疱疹，是病毒性脑炎的主要原因。HSV的生命周期包括一个在粘膜部位的裂解期，在此期间所有病毒基因都得到表达，以及一个在神经元中的潜伏期，在此期间基因表达极为有限。潜伏期是一个永久的蓄水池，HSV周期性地重新激活，造成严重的皮肤粘膜损伤。再激活是非常频繁的，并导致病毒脱落。尽管有有效的抗病毒药物，但潜伏期使HSV难以治愈，而且目前还没有有效的HSV疫苗。更好地治疗和了解疱疹性眼病是NEI角膜疾病项目的既定目标。嗜神经疱疹病毒迅速关闭受感染细胞中的蛋白质合成。对于单纯疱疹病毒，负责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rna酶，可诱导宿主mrna的快速失稳。所有嗜神经疱疹病毒都有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）会破坏宿主mRNA的稳定性。这一特性是一个关键的毒力决定因素。我们发现vhs的活动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重要作用。Vhs活性改变先天免疫反应的大小，我们确定了Vhs的功能域，表征了其在被膜中活性的关键域，并表明Vhs在神经系统中具有活性。此外，缺乏vhs的病毒是唯一有效的治疗性疫苗（美国专利#5698431）。我们目前的工作假设是，由于vhs改变先天免疫功能和促进复制的能力，它决定了体内感染的结果。在动物模型中，先天免疫在决定病毒感染的结果和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对HSV非常敏感。因此，需要更好地了解对病毒感染的先天反应。此外，更好地定义vhs功能将确定针对HSV疾病的治疗干预目标，并有助于设计HSV疫苗。此外，有新的证据表明，诱导宿主mRNA降解也是其他人类病原体的发病机制决定因素。因此，病毒诱导的RNA不稳定的特异性抑制剂可能具有广谱抗病毒药物的价值。因此，这项工作具有广泛的兴趣和应用。公共卫生相关性：在发达国家，单纯疱疹病毒（HSV）是导致非创伤性失明的主要原因，也是唇疱疹、生殖器疱疹和脑炎的病原体。我们工作的目标是在小鼠眼模型中确定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治疗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.