Targeting Apoptosis and Immune Control of Epstein-Barr Virus Infected Tonsillar B Cells

 描述(申请人提供)：爱泼斯坦-巴尔病毒(EBV)是一种伽玛疱疹病毒，感染全球近95%的成年人。针对病毒的强有力的适应性免疫反应可以预防大多数感染者的疾病。然而，免疫抑制，如在HIV-1感染期间，可能会促进潜伏的EBV驱动的B细胞淋巴瘤。我们的最终目标是定义EBV建立潜伏期的机制以及这些过程是如何出错导致疾病的。在这项建议中，我们的目标是描述在原代扁桃体B细胞中新描述的EBV感染的早期潜伏期，以及EBV介导的生存和免疫逃避的机制对于建立和维持潜伏库非常重要。我们的中心假设是，在感染的前两周，EBV通过其EBV核抗原(EBNA)蛋白促进B细胞的增殖和存活；而在随后的感染过程中，EBNAs和潜伏膜蛋白1(LMP1)是维持永生状态所必需的。我们认为，这一双相EBV潜伏基因表达计划的重要性在于防止细胞毒性T细胞早期识别EBV感染的B细胞，促进长期潜伏感染细胞库的有效播种。我们根据初步数据提出了我们的中心假设，这些数据描述了EB病毒感染外周血B细胞后的临时病毒和宿主基因表达程序和生存机制，其中我们发现在扁桃体B细胞感染后早期，病毒EBNA蛋白在扁桃体B细胞中高水平表达。 缺乏明显水平的病毒LMP。重要的是，这种潜伏型(IIb)已经在EBV相关的移植后淋巴瘤和HIV淋巴瘤中观察到。因此，这项研究的基本原理是，了解支持EBV潜伏期IIb感染的机制可以确定EBV相关淋巴瘤的关键治疗靶点，并可能有助于我们理解EBV感染的时间动态和对这种普遍存在的口腔传播病原体的适应性免疫反应。我们计划通过以下三个具体目标来验证我们的假设并完成该建议中概述的目标：1)确定调节病毒基因表达从早期、仅EBNAs(潜伏期IIb)到晚期、EBNAs+LMPs(潜伏期III)的机制，2)确定早期、非依赖于NFκB的和晚期的、依赖于κB的EB病毒感染的扁桃体B细胞存活的机制，以及3)确定低LMP1/NFκB活性对EB病毒感染的B细胞外周血和扁桃体B细胞免疫识别、激活和杀伤B细胞的影响。

 DESCRIPTION (provided by applicant): Epstein-Barr virus (EBV) is a gamma-herpesvirus that infects nearly 95% of adults worldwide. A potent adaptive immune response against the virus prevents disease in the majority of those infected. However, immune suppression, such as during HIV-1 infection, can promote latent EBV-driven B-cell lymphomas. It is our ultimate goal to define the mechanisms by which EBV establishes latency and how these processes go awry leading to disease. In this proposal, we aim to characterize a newly described early latent phase of EBV infection in primary tonsillar B cells and the mechanisms of EBV-mediated survival and immune evasion important for establishing and maintaining the latency reservoir. It is our central hypothesis that EBV promotes B-cell proliferation and survival through its EBV nuclear antigen (EBNA) proteins during the first two weeks of infection; while later during infection the EBNAs and latent membrane protein 1 (LMP1) are required for survival in the immortalized state. We propose that the importance of this biphasic EBV latent gene expression program is to prevent early recognition of EBV-infected B cells by cytotoxic T cells promoting efficient seeding of the long-term latently infected cell reservoir. We have formulated our central hypothesis based on preliminary data characterizing the temporal viral and host gene expression programs and survival mechanisms following EBV infection of peripheral blood B cells where we found that early after tonsillar B-cell infection, the viral EBNA proteins are expressed at high levels in the absence of appreciable levels of the viral LMPs. Importantly, this latency type (IIb) has been observed in EBV-associated post-transplant and HIV lymphomas. Therefore, the rationale for this proposed research is that understanding the mechanism supporting latency IIb infection by EBV may identify critical therapeutic targets for EBV-associated lymphomas and may inform our understanding of the temporal dynamics of EBV infection and the adaptive immune response to this ubiquitous orally-transmitted pathogen. We plan to test our hypothesis and complete the objectives outlined in this proposal through the following three specific aims: 1) Determine the mechanism regulating the switch in viral gene expression from early, EBNAs only (latency IIb), through late, EBNAs + LMPs (latency III), phases of primary tonsillar B-cell infection, 2) Determine the mechanism of early, NFκB-independent and late, NFκB- dependent EBV-infected tonsillar B-cell survival, and 3) Define the consequences of low LMP1/NFκB activity on EBV-infected B-cell peripheral blood and tonsillar B-cell immune recognition, activation, and killing b T cells.