Mechanisms of Epstein-Barr Virus Persistence

描述（由申请人提供）： EB病毒（EBV）是一种非常成功的病原体，能够在其人类宿主的B淋巴细胞内建立终身潜伏感染，当感染延迟至24小时，健康个体中的显性疾病限于约40%的个体中的自限性单核细胞增多症。 人生的第二个十年然而，细胞免疫的破坏，特别是作为AIDS的结果，仍然是EBV相关淋巴瘤和淋巴增生性疾病发展的重要风险因素，强调了EBV与其宿主之间存在的高度进化的平衡。这种平衡的建立最初依赖于九种EBV潜伏相关蛋白和病毒miRNA的子集的高度协调和控制的表达-潜伏期III（Lat III）程序。本申请中提出的研究的长期目标是充分理解通过调节Lat III程序促进EBV持久性的机制，即，在持续感染的早期建立阶段。该阶段的中心是由两个共同启动子（Wp和Cp）之一表达的六种EBV核蛋白（EBNA）的家族。EBNAs主要作为转录因子发挥作用（EBNA 1也是病毒基因组维持蛋白），通过调节细胞和病毒潜伏基因的表达来促进病毒持续存在。本申请的基础是我们最近发现了两种控制EBNA表达的新的和明显的转录后调节机制，以及发现了一种新的潜伏相关EBV RNA家族，其可能通过潜在的调节功能和/或新的蛋白质表达对Lat III有贡献。在目标1下，我们提出鉴定负责依赖于EBNA启动子Wp的蛋白质表达的反式阻遏的EBV基因，并最终鉴定其作用机制以及对EBV生物学和持久性的重要性。在目的2中，我们建议定义病毒基因组的EBV BHLF 1基因位点对潜伏感染的贡献，扩展初步数据，表明BHLF 1可能在潜伏感染期间作为长非编码RNA（lncRNA）对EBNA mRNA的正确剪接很重要。最后，在目标3中，我们将表征和探索跨越EBNA启动子Cp的新型RNA转录物家族对EBV潜伏期的贡献。

DESCRIPTION (provided by applicant): Epstein-Barr virus (EBV) is an extremely successful pathogen, being able to establish a lifelong latent infection within B lymphocytes of its human host, with overt disease in healthy individuals restricted to a self- limiting mononucleosis in ~40% of individuals when infection is delayed until the second decade of life. However, a breakdown in cellular immunity, particularly as a consequence of AIDS, remains a significant risk factor for development of EBV-associated lymphoma and lymphoproliferative disease, underscoring the highly evolved equilibrium that exists between EBV and its host. Establishment of this equilibrium is dependent initially on a highly coordinated and controlled expression of the nine EBV latency-associated proteins and a subset of the viral miRNAs - the latency III (Lat III) program. The long-term objective of the research proposed in this application is to fully understand the mechanisms that contribute to EBV persistence through regulating the Lat III program, i.e., during the early establishment phase of persistent infection. Central to this phase are a family of six EBV nuclear proteins (EBNAs) that are expressed from one of two common promoters (Wp and Cp). The EBNAs primarily function as transcription factors (EBNA1 is also the viral genome-maintenance protein) to promote virus persistence through their regulation of cellular and viral latency-gene expression. The foundation for this application are our recent discoveries of two novel and apparent posttranscriptional regulatory mechanisms of controlling EBNA expression, and the discovery of a novel family of latency- associated EBV RNAs that may contribute to Lat III through a potential regulatory function and/or novel protein expression. Under Aim 1, we propose to identify the EBV gene responsible for the trans-repression of protein expression dependent on the EBNA promoter Wp, and ultimately its mechanism of action and importance to EBV biology and persistence. In Aim 2 we propose to define the contribution of the EBV BHLF1 gene locus of the virus genome to latent infection, expanding on preliminary data that suggests BHLF1 may function during latent infection as long noncoding RNA (lncRNA) important for the proper splicing of the EBNA mRNAs. Finally, in Aim 3 we will characterize and explore the contribution to EBV latency of a family of novel RNA transcripts that span the EBNA promoter Cp.