疱疹病毒是一个古老的家族，一旦入侵宿主便能建立持续性感染，使宿主成为终身携带者。近期临床和基础研究数据表明，裂解复制对疱疹病毒的持续性感染及致病性至关重要，但裂解复制特别是病毒颗粒组装与释放的分子机制仍有诸多不明之处。间质（tegument）是疱疹病毒特有的一个结构成分，位于囊膜和核衣壳之间，由多种病毒蛋白组成，在病毒颗粒的组装与释放过程中起着关键的桥梁作用。我们以鼠疱疹病毒68为模型，对γ疱疹病毒的组装释放过程进行了系统研究，鉴定出在此过程中起关键作用的间质蛋白ORF33、ORF45及ORF52等。本项目拟在此基础上，综合多种技术手段，解析ORF33、ORF45介导病毒衣壳的核释放以及病毒颗粒在细胞质中成熟的分子机制，阐明ORF52及其相互作用蛋白ORF42在病毒颗粒组装与释放中的作用与机理。研究结果将帮助深入理解疱疹病毒裂解复制的分子机理，为防控病毒持续性感染提供理论依据。

Herpesviruses constitute an ancient family, whose members can efficiently establish persistent, life-long infections in their respective hosts. Recent progress in both basic and clinical research has shown that viral lytic replication plays a critical role in viral persistent infections and the associated pathogenesis, yet much remains unknown about the molecular mechanisms underlying herpesvirus lytic replication, especially the late phase of virion assembly and egress. Composed of many viral proteins, tegument is a unique structure of a herpesvirus particle and occupies the space between nucleocapsid and envelope. Increasing amount of knowledge has indicated that tegument proteins play critical roles in virion morphogenesis by bridging the nucleocapsid and the envelope. Using murine gammaherpesvirus 68 (MHV-68) as a model, we have systematically investigated the virion assembly and egress process of gammaherpesviruses and identified several tegument proteins that play essential roles in this process, including ORF33, ORF45 and ORF52. In this application, we plan to integrate molecular and cellular biology, genetics, proteomics and bioimaging approaches, and propose the following aims: 1) to investigate the molecular mechanisms mediating the functional roles of ORF33 and ORF45 in nuclear egress of MHV-68 nucleocapsids; 2) to study the molecular mechanisms mediating the essential roles of ORF33 and ORF45 in cytoplasmic maturation of MHV-68 virions; 3) to identify viral and cellular proteins that interact with ORF52 and investigate the role of these interactions in mediating secondary envelopment of virions as well as the underlying molecular mechanisms. Our results will lead to a deeper understanding of the molecular mechanisms involved in herpesvirus lytic replication and provide insights into developing new therapeutic approaches to prevent and control viral persistent infections.