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，在美国每年有20多万例。HSV可引起人类多种眼部疾病，从自限性树突状上皮角膜炎、结膜炎、睑缘炎到坏死性基质角膜炎。此外，单纯疱疹病毒通常会引起唇疱疹、生殖器溃疡，并且是病毒性脑炎的主要原因。单纯疱疹病毒和其他嗜神经性疱疹病毒的生活史特征是在角膜和皮肤等周围部位感染的裂解期，在此期间所有病毒基因都得到表达，在神经元中感染的潜伏期，在此期间基因表达极其有限。潜伏期代表了病毒的终生来源，这种病毒可以周期性地重新激活，导致严重的眼部和其他黏膜皮肤损伤，而建立终生潜伏期的能力使单纯疱疹病毒对治愈具有抵抗力。 嗜神经性疱疹病毒的一个特征是它们能够迅速切断它们感染的细胞中的大分子合成。对于1型单纯疱疹病毒(HSV-1)和2型单纯疱疹病毒(HSV-2)，负责这种关闭的基因是被称为病毒粒子宿主关闭蛋白或VHS的UL41基因的产物。所有嗜神经性疱疹病毒都有UL41基因的同源基因，尽管在建立神经元潜伏期的病毒中这种基因保守的原因尚不清楚。我们以前资助的研究表明，VHS活动在眼睛的感染和损害、眼周疾病的发展和潜伏期的建立中起着重要作用。我们已经定义了VHS的结构域，该结构域对于VP16与VP16的相互作用至关重要，从而调节其包装和活性。我们还表明，VHS活动可以改变对HSV的免疫反应的大小。此外，我们已经证明，VHS缺乏的病毒是预防复发疱疹感染的有效疫苗。这些成果完全符合NEI的角膜疾病计划规定的研究目标。 这项建议的目的是在我们以前发现的基础上，进一步研究多功能VHS蛋白的作用机制及其在发病机制和眼部疾病中的影响。我们提出的假设是，VHS通过改变干扰素诱导的激酶PKR的活性来帮助使HSV对干扰素产生抗药性。此外，我们验证了VHS活性通过控制抗原提呈改变对病毒感染细胞的识别，从而形成有利于病毒的适应性免疫反应的假设。最后，我们将确定VHS的结构域，这些结构域对于HSV与神经元的相互作用非常重要，也是病毒潜伏的位置，并确定HSV和VHS如何改变神经元中的基因表达模式。我们认为，更好地定义VHS功能的机制和范围将为HSV眼部疾病的治疗干预提供靶点，并有助于HSV疫苗的设计。

DESCRIPTION (provided by applicant): Herpes simplex virus (HSV) keratitis is a leading cause of non-traumatic blindness in developed countries, with more than 200,000 cases per year in the USA. HSV can cause a variety of ocular diseases in humans ranging from self-limiting dendritic epithelial keratitis, conjunctivitis, and blepharitis to necrotizing stromal keratitis. In addition, HSV commonly causes cold sores, genital sores, and is a leading cause of viral encephalitis. The life cycles of HSV and other neurotropic herpesviruses are characterized by a lytic phase of infection at peripheral sites such as the cornea and skin during which all virus genes are expressed, and a latent phase of infection in neurons, during which gene expression is extremely limited. Latency represents a lifelong source of virus which can reactivate periodically causing severe ocular and other mucocutaneous damage, and the ability to establish lifelong latency renders HSV resistant to cure. One hallmark of the neurotropic herpesviruses is their ability to rapidly shut off macromolecular synthesis in the cells that they infect. For HSV type 1 (HSV-1) and HSV-2 the gene responsible for this shutoff is the product of the UL41 gene known as the virion host shutoff protein or vhs. All of the neurotropic herpesviruses have a homolog of the UL41 gene, although the reason for this gene conservation among viruses that establish latency in neurons is not known. Our previously funded studies have shown that vhs activity plays an essential role in infection and damage of the eye, in the development of periocular disease, and in the establishment of latency. We have defined a domain of vhs that is critical for its interaction with VP16 and thereby regulates both its the packaging and activity. We have also shown that vhs activity can alter that magnitude of immune responses to HSV. In addition we have shown that viruses deficient in vhs are effective vaccines for the prevention of recurrent herpetic infections. These accomplishments are in complete accordance with the stated research goals of the Corneal Diseases Program of the NEI. The objectives of this proposal are to build upon our previous findings and further investigate the mechanisms of action of the multifunctional vhs protein and its impact upon pathogenesis and ocular disease. We address the hypothesis is that vhs helps render HSV resistant to interferon through its ability to alter the activity of the interferon-induced kinase PKR. In addition, we test the hypothesis that vhs activity alters the recognition of virus-infected cells through control of antigen presentation, thereby shaping the adaptive immune response in favor of the virus. Finally we will identify the domains of vhs, which are important for the interaction of HSV with neurons, the site of latency for the virus, and identify how HSV and vhs alter gene expression patterns in neurons. We reason that a better definition of the mechanisms and domains of vhs function will provide targets for therapeutic intervention against HSV ocular disease, as well as aiding in the design of HSV vaccines.