戊型肝炎病毒ORF3通过调控TLR3和RIG-I介导的NF-κB和IRF3信号进行免疫逃逸的研究

It is estimated that 2 billion people have been infected with hepatitis E virus（HEV）around the world, and 300 000 deaths occur annually. However, the detailed pathogenesis of acute and chronic hepatitis E（HE）are unclear. Nowadays, chronic HE becomes the research focus at domestic and abroad. We have previously found that HEV open reading frame 3 (ORF3) not only inhibited TNFα-induced nuclear factor-κappa B (NF-κB ) signaling, but also suppressed the activity of NF-κB mediated by TLR3, while toll like receptor 3 (TLR3）and retinoic acid induced gene I (RIG-I) induced IRF3 signaling is an important pathway of the host innate immune mediated by virus. Therefore, we hypothesized that ORF3 may be involved in the immune escape through the regulation of TLR3 and (or) RIG-I mediated NF-κB and IRF3 signaling. we construct firstly the HEV cDNA, ORF3 cloning and ORF3 mutant, then observe the effect of ORF3 on NF-κB and IRF3 signaling mediated by TLR3 and RIG-I, as well as the maturation and activated status of host dentritic cells. Our aim is to clarify the role and mechanism of ORF3 in acute and chronic HE, and then explore a switch on the prevention and treatment of chronic HEV infection.

全球约20亿人感染戊型肝炎病毒（hepatitis E virus, HEV），每年有30万人死于HEV感染所引起的急慢性肝病，但戊型肝炎（hepatitis E, HE）发生及慢性化的机制仍不明确。目前，国内外研究的焦点集中于HE慢性化研究上。我们前期发现，HEV开放读码框3(open reading frame 3, ORF3)对TNFα及TLR3介导的NF-κB信号均发挥抑制作用，而TLR3和RIG-I诱导的IRF3信号是病毒调控宿主固有免疫的重要途径。我们推测ORF3可能通过调控TLR3和（或）RIG-I介导的NF-κB和IRF3信号实现免疫逃逸。我们拟通过构建HEV cDNA、ORF3克隆及其突变体，研究ORF3对TLR3、RIG-I介导的NF-κB、IRF3信号及树突状细胞成熟活化的影响，阐明ORF3在HE发生及慢性化中的作用及机制，为防治HE慢性化开辟新思路。

近年来,关于戊型肝炎(HE)的报道越来越多。在发展中国家,戊型肝炎病毒(HEV) 会通过粪-口途径引起水源性的大规模爆发以及一些急性自发性的散发病例。戊型肝炎病毒是引起本地流行和自限性散发疾病的原因,当然也会导致急性肝炎,少数的暴发性肝衰竭以及在中晚期孕妇人群中引起高达20%的致死率,这给我们的社会带来了极大的危害。本课题的研究表明：1）1型HEV ORF3是通过TRADD-RIP1复合物抑制了TLR3介导的NF-κB信号通路的活化。2）3型HEV在C3A细胞中通过ISG15蛋白抑制I型干扰素(IFN-α和IFN-β)的表达。3）基因l型HEV ORF3能够抑制DC细胞成熟。综上所述，我们的研究发现HEV ORF3能够促进戊肝病毒复制, 提出了新的理论观点,加深了戊肝病毒在细胞内致病机制的理解,为临床抗击戊肝感染提供了新的治疗方向。