I型单纯疱疹病毒UL2蛋白抑制TNF-α诱导NF-κB活性的分子机制研究

Herpes simplex virus 1 (HSV-1), a prevalent human virus that can lead to a variety of diseases, has become one of the vital pathogens that is severely harmful to human health, yet no efficient drug or vaccine has been developed. Innate immunity is the first line of host defense against viral invasion, and nuclear factor κB (NF-κB) plays a very important role in anti-HSV-1 infection. It is shown that HSV-1 can encode some proteins to control the host innate immunity by inhibiting the NF-κB activity in different ways, however, whether there are other HSV-1 proteins also participate in this process remains unknown. Our preliminary data demonstrate that UL2 can effectively inhibit the tumor necrosis factor-α (TNF-α)-mediated NF-κB promoter activity, and this inhibition takes place at the p65 level, suggesting that UL2 can serve as a new antagonist of NF-κB signaling pathway. Accordingly, this study is intended to further deeply analyse the molecular mechanism of UL2 inhibiting the NF-κB signaling pathway in the viral infected cells and animal models by utilizing dual luciferase reporter system, as well as a number of molecular biology, immunology and virology techniques. In conclusion, these works will not only assist us to understand the pathogenesis of HSV-1, but also offer a theoretical foundation for the further design of new antiviral drug target and development of efficient vaccine against HSV-1.

I型单纯疱疹病毒（HSV-1）在人群中的感染极为普遍，可引起多种疾病，已成为严重危害人类健康的重要病原之一，目前尚无有效的药物和疫苗。天然免疫是宿主抵抗病毒入侵的第一道防线，其中核因子κB（NF-κB）在抗HSV-1感染中扮演着重要的角色。研究发现，HSV-1可以编码一些蛋白通过不同方式抑制NF-κB活性来调控宿主的天然免疫，然而，是否存在其它HSV-1蛋白也参与这个过程尚不明确。我们的预实验结果表明，HSV-1 UL2蛋白能明显抑制TNF-α诱导的NF-κB启动子活性，并且它是在p65水平发挥抑制作用，说明UL2是NF-κB通路新的拮抗剂。因此，本项目拟采用双荧光素酶报告系统结合多种分子生物学、免疫学和病毒学实验在病毒感染的细胞和动物水平深入阐明UL2抑制NF-κB信号通路的分子机制，这不仅有助于加深我们对HSV-1致病机制的认识，也可为进一步的抗病毒药物靶点设计和疫苗研制提供理论依据。

I型单纯疱疹病毒(HSV-1)是一种大的双链DNA病毒，它编码至少80种病毒蛋白，其中许多蛋白参与病毒与宿主的相互作用，这有利于病毒的生存和增殖。然而，一些HSV-1编码蛋白质的生物学功能还不完全清楚。宿主的天然免疫系统是抵抗病原入侵的第一道防线，而核因子-κB（Nuclear factor κB，NF-κB）激活是主要的抗病毒反应，可由不同途径细胞受体诱导的多种信号触发。在本研究中，我们首次发现HSV-1 UL2蛋白可以拮抗由肿瘤坏死因子（Tumor necrosis factor-α，TNF-α）所激活的NF-κB信号通路。免疫共沉淀（Co-Immunoprecipitation, Co-IP）实验结果显示，UL2可以与内源性NF-κB亚基的p65及p50相互作用，而且UL2的aa9-17是UL2抑制NF-κB激活及与p65/p50相互作用的关键区域。另外，UL2能够与p65的IPT (Immunoglobulin-like plexin transcription factor) 结构域结合，但不影响p65/p50二聚体的形成和入核。UL2可以通过削弱TNF-α诱导p65在Ser536位点的磷酸化来抑制NF-κB的活性, 进而抑制NF-κB调控的下游炎症细胞因子白介素-8 (Interleukin-8，IL-8)的表达。总之，本研究发现UL2可以通过负调控TNF-α诱导NF-κB的活性来帮助HSV-1逃逸宿主的天然免疫，提示UL2可能在平衡HSV-1感染与宿主NF-κB信号通路之间起着重要的作用。