Regulation of the Epstein-Barr Virus Lytic Switch

摘要 EB病毒（EBV）在全球95%的成年人中建立终身感染。EBV 引起传染性单核细胞增多症、淋巴瘤、鼻咽癌和胃癌， 毛状白斑病EB病毒通过唾液在宿主之间传播， 穿过口腔和扁桃体上皮到达B细胞室。在B细胞上 感染后，将~170倍酶线性双链DNA（dsDNA）EBV基因组递送至 原子核EBV然后使用一系列潜伏期程序来导航B细胞区室， 并占据记忆B细胞区最终，在细胞之间传播， 为了转移到新的宿主，EBV必须经历裂解性复制，其中 表达了近80种病毒蛋白并产生了感染性病毒粒子。裂解复制是 越来越多地与肿瘤发生有关。然而，关于病毒是如何传播的， 裂解开关被控制。因此，我们使用人类全基因组CRISPR/Cas9筛选， 鉴定控制病毒裂解开关的宿主因子。我们分析了一个主机因素网络， 抑制裂解再活化，以转录因子MYC为中心，包括粘附素，FACT， STAGA和Mediator。MYC或对MYC表达重要的因子的耗尽，重新激活 溶解周期，包括伯基特异种移植物。MYC结合裂解型EB病毒基因组起源 复制并抑制其与裂解周期起始子BZLF 1启动子的成环。我们的中央 假设MYC：MAX通过调节病毒基因组来控制EBV裂解开关 循环挤出。我们的目标是（1）确定MYC在调节oriLyt环挤出中的关键作用， 控制EBV裂解开关;（2）定义MYC门控粘附素在oriLyt环调节中的作用 （3）明确MYC门控CTCF在调节oriLyt中的作用 环挤出以控制EBV裂解开关。总的来说，这些研究预计将确定 EBV如何颠覆宿主DNA环挤出途径以控制病毒裂解开关。 因此，我们的研究可能支持开发合理的裂解诱导治疗策略， EBV相关疾病的治疗。

Abstract Epstein-Barr virus (EBV) establishes lifelong infection in 95% of adults worldwide. EBV causes infectious mononucleosis, lymphomas, nasopharyngeal and gastric cancer, and oral hairy leukoplakia. EBV is transmitted between hosts through saliva, from which it translocates across the oral cavity and tonsillar epithelium to reach the B-cell compartment. Upon B-cell infection, the ~170 kilobase linear double-stranded DNA (dsDNA) EBV genome is delivered to the nucleus. EBV then uses a series of latency programs to navigate the B-cell compartment, and colonize the memory B-cell compartment. Ultimately, to spread between cells and to the tonsillar epithelium for transfer to a new host, EBV must undergo lytic replication, in which nearly 80 viral proteins are expressed and infectious virion are produced. Lytic replication is increasingly implicated in oncogenesis. Yet, much remains to be learned about how the viral lytic switch is controlled. We therefore used a human genome-wide CRISPR/Cas9 screen to identify host factors that control the viral lytic switch. Our analyses a network of host factors that repress lytic reactivation, centered on the transcription factor MYC, including cohesins, FACT, STAGA, and Mediator. Depletion of MYC or factors important for MYC expression, reactivated the lytic cycle, including in Burkitt xenografts. MYC bound the EBV genome origin of lytic replication and suppressed its looping to the lytic cycle initiator BZLF1 promoter. Our central hypothesis is that the MYC:MAX control the EBV lytic switch through regulation of viral genome loop extrusion. Our Aims are to (1) Define key MYC roles in regulation of oriLyt loop extrusion to control the EBV lytic switch; (2) Define MYC-gated cohesin roles in regulation of oriLyt loop extrusion in EBV lytic switch control (3) Define MYC-gated CTCF roles in regulation of oriLyt loop extrusion to control the EBV lytic switch. Collectively, these studies are expected to identify how EBV subverts host DNA loop extrusion pathways to control the viral lytic switch. Our studies may therefore support strategies to develop rational lytic induction therapeutic therapies for EBV-associated diseases.