Genetics and Functions of HSV Membrane Fusion Proteins

描述（由申请人提供）：疱疹病毒是重要人类疾病（包括某些癌症）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病变的常见原因;而单纯疱疹病毒2型（HSV-2）则引起生殖器病变、脑膜炎和新生儿感染。 单纯疱疹病毒（HSV）每年感染30多万人，是仅次于创伤的角膜致盲性疾病。单纯疱疹病毒（HSV）通过复杂的、连续的脱膜和再膜过程获得病毒包膜，其中被膜蛋白和包埋在细胞内膜中的病毒糖蛋白之间的相互作用起着重要作用。多跨膜蛋白UL 20 p和gK直接参与细胞内病毒体的形成，因为缺失任一基因都会导致无包膜衣壳在细胞质中的急剧积累。此外，UL 20 p和gK都具有合胞体突变，这表明它们参与病毒体增殖和排出期间的膜融合现象，以及病毒诱导的细胞融合。我们已经表明，HSV-1 gK和UL 20 p是共同依赖的细胞表面表达和TGN定位，他们的物理相互作用。此外，我们还发现UL 20 p可以与gB发生物理相互作用。本论文主要研究单纯疱疹病毒（HSV）糖蛋白K（gK）和UL 20蛋白（UL 20 p）在病毒诱导的细胞融合和细胞质病毒粒子增殖中的作用。该授权申请的主要假设是：i）gK和UL 20 p相互作用并调节gB介导的细胞融合; ii）gK和UL 20 p通过结合被膜蛋白在细胞质病毒体构建中作为病毒体结构组分起作用。具体目标是：I）表征UL 20 p与gK的相互作用并研究它们向细胞表面的协同转运、胞吞作用和TGN共定位; II）研究UL 20 p与gK和gB的相互作用对gB介导的病毒诱导的细胞融合的作用; III）研究UL 20 p在细胞质病毒体增殖中的作用。阐明gK，UL 20 p和gB之间的功能相互关系，以及gK，UL 20 p和被膜蛋白之间的关系，将有助于定义病毒蛋白质-蛋白质的相互作用参与感染性病毒的生产，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.