Genetics and Functions of HSV Membrane Fusion Proteins

描述(申请人提供)：疱疹病毒是包括某些癌症在内的重要人类疾病的病原体。单纯疱疹病毒1型(HSV-1)是成人散发性脑炎、角结膜炎和口腔粘膜皮肤损害的常见原因；而单纯疱疹病毒2型(HSV-2)会导致生殖器损害、脑膜炎和新生儿感染。在美国，单纯疱疹病毒每年感染超过30万人，是仅次于创伤的角膜致盲原因。单纯疱疹病毒粒子通过复杂的、顺序的去包膜和再包膜过程获得病毒包膜，其中被膜蛋白和嵌入细胞膜的病毒糖蛋白之间的相互作用起着重要作用。多膜跨膜蛋白UL20p和gk直接参与了细胞内病毒粒子的包膜，因为这两个基因的缺失都会导致未被包膜的衣壳在细胞质中大量积聚。此外，UL20p和Gk都含有合胞体突变，表明它们参与了病毒粒子包膜和出口过程中的膜融合现象，以及病毒诱导的细胞融合。我们已经证明了HSV-1gk和UL20p在细胞表面的表达和TGN的定位是相互依赖的，并且它们之间存在物理上的相互作用。此外，我们还发现UL20P可以与GB发生物理作用。拟议的研究集中在单纯疱疹病毒(HSV)糖蛋白K(GK)和UL20蛋白(UL20p)在病毒诱导的细胞融合和细胞质病毒粒子包膜中的作用。这一拨款申请的主要假设是：1)GK和UL20P相互作用并调节GB介导的细胞融合；2)GK和UL20P通过与被膜蛋白结合，在细胞质病毒粒子被膜中作为病毒粒子结构成分发挥作用。这些研究的具体目的是：1)研究UL20p与gk的相互作用及其与细胞表面的配位转运、内吞作用和TGN共定位；ii)研究UL20p与gk和gB的相互作用在gB介导的病毒诱导的细胞融合中的作用；iii)研究UL20p在细胞质病毒包被中的作用。阐明gk、UL20p和gB之间的功能相互关系以及gk、UL20p和被膜蛋白之间的功能相互关系将有助于确定参与感染病毒产生的病毒蛋白-蛋白相互作用，并可能有助于开发新的抗病毒策略。

DESCRIPTION (provided by applicant): Herpesviruses are etiologic agents of important human diseases including certain cancers. Herpes simplex virus type 1 (HSV-1) is a frequent cause of adult sporadic encephalitis, keratoconjunctivitis and oral mucocutaneous lesions; whereas, herpes simplex virus type 2 (HSV-2) causes genital lesions, meningitis and neonatal infections. HSV infects over 300,000 individuals annually, and they are second only to trauma as a cause of corneal blindness in the U.S.A. Herpes simplex virions acquire viral envelopes via a complicated, sequential de-envelopment and re-envelopment process, in which interactions between tegument proteins and viral glycoproteins embedded in intracellular membranes play important roles. The multi-membrane spanning proteins, UL20p and gK, have been directly implicated in intracellular virion envelopment, since deletion of either gene results in drastic accumulation of unenveloped capsids in the cytoplasm. In addition, both UL20p and gK harbor syncytial mutations suggesting that they are involved in membrane fusion phenomena during virion envelopment and egress, as well as virus-induced cell fusion. We have shown that HSV-1 gK and UL20p are co-dependent for cell-surface expression and TGN localization, and that they physically interact. In addition, we have found that UL20p can physically interact with gB. The proposed investigations focus on the role of herpes simplex virus (HSV) glycoprotein K (gK) and UL20 protein (UL20p) in virus-induced cell fusion and cytoplasmic virion envelopment. The main hypotheses of this grant application are: i) gK and UL20p interact and regulate gB-mediated cell fusion; ii) gK and UL20p function as virion structural components in cytoplasmic virion envelopment by binding to tegument proteins. The specific aims are: I) to characterize UL20p interactions with gK and investigate their coordinate transport to cell-surfaces, endocytosis and TGN co-localization; II) to investigate the role of UL20p interactions with gK and gB on gB-mediated virus-induced cell fusion; III) to investigate the role of UL20p in cytoplasmic virion envelopment. Elucidations of functional interrelationships between gK, UL20p and gB as well as between gK, UL20p and tegument proteins will help define viral protein-protein interactions involved in infectious virus production and may assist in the development of new antiviral strategies.