线粒体动态变化在戊型肝炎病毒持续感染过程中的作用及机制研究

The outcomes of HEV infection are diverse, ranging from asymptomatic carrier, self-limiting acute infection, fulminant hepatitis to persistent infection. This is closely associated with the immunological status of the host. ..Mitochondrion is a double membrane-bound organelle present in all eukaryotic organisms. Recent studies have highlighted the interaction between mitochondria and virus, which ultimately affect the infection course of the virus. Mitochondria are highly dynamic organelles that constantly undergo fusion (elongation of mitochondria) and fission (division of mitochondria), which are sensitive to the alteration of cellular environmental or metabolic conditions, such as oxygen stress, toxic exposure and viral infection. ..In this project, we have investigated the interaction and regulation of HEV infection by mitochondrial dynamics in patients and in vitro. Aggregated mitochondria were observed in the liver tissues of HEV patients. Morphological alteration with indications of mitochondrial injury is potentially associated with more severe clinical manifestations in HEV patients. In vitro, cells that electroporated with HEV RNA or inoculated of HEV infectious particles display elongated mitochondria, a hallmark of mitochondrial fusion. Furthermore, functional assay by gene silencing of key mitochondrial fusion regulators demonstrated that HEV infection triggered mitochondrial fusion in turn facilitate viral replication. However, the mechanism is unclear. Thus the aim of this study is to investigate how the HEV-induced mitochondrial fusion regulate HEV relication in respect to autophagy process and cellular innate immunity. The deeper understaiding of mitochondria based HEV viral-host interaction will offer new insight into HEV pathogenesis and clinical management, providing new opportunity for development of efficient aiti-HEV strategies.

戊型肝炎病毒（HEV）持续复制和慢性化机制尚不清楚，同时也没有FDA批准的抗HEV的药物。近十年研究发现线粒体动态对调控细胞稳态及病毒复制至关重要。细胞内的线粒体并非处于静止状态，而是在应激状态下不断进行融合-分裂的动态变化。多项研究证明病毒感染可以导致线粒体动态变化，相应地，这种线粒体动态变化又会特异性地调控病毒复制。我们前期体内体外研究都发现HEV感染可以诱导线粒体融合从而促进病毒持续复制，但其机制尚不清楚。由于线粒体动态变化可以特异性调控细胞自噬及宿主天然免疫，而我们前期研究发现HEV感染可以诱导细胞自噬，但却不能充分激活天然免疫。因此我们探讨HEV感染导致的线粒体融合是否通过调控自噬及干扰天然免疫来影响HEV复制，同时明确线粒体动态调控HEV复制的作用靶点，为阐明HEV和宿主细胞相互作用关系及HEV慢性化机制、开发新的靶向线粒体动态变化的抗病毒治疗方法奠定基础。

.本研究构建了戊肝病毒(HEV) 体外高复制感染模型，可持续稳定感染人和动物的多种细胞系。同时利用人源肝脏类器官成功建立了HEV体外复制和感染模型，该模型支持感染的整个生命周期。由于类器官是从多能干细胞或者器官祖细胞生成的，它们分化并自发形成与体内来源组织或器官高度相似的结构，在保持源组织/器官细胞类型的结构、组成、多样性和功能方面具有独特优势，该系统将极大推动戊肝病毒与宿主互作以及抗病毒药物筛选的研究。基于HEV体外模型的建立，我们还揭示了HEV激活天然免疫反应及炎症反应机制，并解释了该激活过程所需的天然免疫调节因子。临床研究方面，阐明了基因4型HEV感染与神经系统疾病相关性。通过分析各类非创伤性神经系统损伤中HEV感染率，发现基因4型HEV感染与病毒性脑炎具有相关性。开展了国际上首个针对HEV相关肝衰竭的临床大队列研究，揭示了中国人群戊型肝炎患者发生肝衰竭的流行率、近十年的流行趋势、危险因素及预后，发现肝脏本身肝硬化的状态，而非是否有慢性基础肝病以及病因，是戊肝患者是否发生肝衰竭的重要因素，纠正了既往认为基础肝病均会影响戊肝患者预后的认识，大力推动了HEV相关肝衰竭和死亡风险的早期预警。本项目还首次证实了基因4型HEV感染健康人后导致慢性肝炎的证据。此外我们还探究了同HEV同属单正链RNA肝炎病毒的HCV的隐匿性感染，揭示了慢性 HCV 持续病毒学应答 (SVR) 后时代隐匿性 HCV 感染与持续肝组织损伤相关，提示DAA时代丙肝患者达到 SVR 后持续监测意义重大。