Role of Human Apolipoprotein E in Hepatitis B Virus Infection and Morphogenesis

摘要 乙肝病毒是人类肝脏疾病的常见原因，包括慢性肝炎、脂肪变性、 肝纤维化、肝硬变和肝细胞癌。乙肝病毒慢性感染超过2.5亿人 全球，包括美国的125万人。尽管乙肝疫苗在很大程度上促进了 减少新的乙肝病毒感染和肝细胞癌病例，但它并不能为数百名 数百万慢性乙肝病毒携带者。世界卫生组织呼吁消除病毒性肝炎，因为 到2030年成为公共健康的威胁。治疗慢性乙肝的最大挑战是消除 乙肝病毒共价闭合环状DNA(CccDNA)，是持续复制的分子基础。 现有的干扰素和/或核苷类似物的抗病毒疗法可以有效地抑制乙肝病毒的复制 但对HBVccDNA水平无显著影响。因此，迫切需要发现和发展 能够消除慢性乙肝病毒感染的新型抗病毒药物。在这方面，一个更彻底的 对乙肝病毒感染、复制和形态发生的了解对发现新的靶点大有裨益 用于抗病毒药物的发现和开发。通过初步研究，我们发现人类 载脂蛋白E(ApoE)与传染性乙肝病毒密切相关。更重要的是，我们的初步数据表明 载脂蛋白E在乙肝病毒感染和形态发生中都起着关键作用。APOE特异性抗体可以有效地 中和乙肝病毒的传染性。此外，apoE表达下调或apoE基因敲除会导致 显著减少了乙肝病毒的感染和产量。根据这些新发现，我们假设 载脂蛋白E被掺入到乙肝病毒粒子中，在体内的乙肝病毒感染和形态发生中发挥重要作用。这个 本应用的总体目标是确定载脂蛋白E在体内的作用和潜在的分子机制。 促进细胞培养和体内的乙肝病毒感染和形态发生。我们的具体目标是：1)确定 载脂蛋白E在乙型肝炎病毒临床分离株感染和形态发生中的重要性；2)测定载脂蛋白E结合 受体和载脂蛋白E-受体的相互作用对有效的乙肝病毒感染很重要；以及3)说明潜在的 载脂蛋白E促进乙肝病毒形态发生的分子机制成功地完成这项工作 应用将导致关于细胞蛋白在乙肝病毒感染中的作用的范式改变和 形态发生。我们的研究结果也将为发现和研究提供新的分子靶标 开发抗病毒药物以最终消除乙肝病毒感染。

Summary Hepatitis B virus (HBV) is a common cause of human liver diseases, including chronic hepatitis, steatosis, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). HBV chronically infects more than 250 million people worldwide, including 1.25 million in the United States. Although HBV vaccine has greatly contributed to the reduction of new cases of HBV infection and HCC, it does not offer therapeutic benefits to the hundreds of millions of chronic HBV carriers. The World Health Organization has called for the elimination of viral hepatitis as a public health threat by the year 2030. The biggest challenge to curing chronic hepatitis B is the elimination of HBV covalently closed circular DNA (cccDNA), which is the molecular basis for persistent HBV replication. Existing antiviral therapies with interferon and/or nucleoside analogs can effectively suppress HBV replication but do not significantly affect the level of HBV cccDNA. Thus, there is an urgent need to discover and develop new classes of antiviral drugs capable of eliminating chronic HBV infection. In this regard, a more thorough understanding of HBV infection, replication, and morphogenesis holds a great promise to identify novel targets for antiviral drug discovery and development. Through preliminary studies, we have discovered that human apolipoprotein E (apoE) is associated with infectious HBV. More importantly, our preliminary data suggest that apoE plays critical roles in both HBV infection and morphogenesis. ApoE-specific antibodies could efficiently neutralize HBV infectivity. Also, knockdown of apoE expression or knockout of apoE gene resulted in a remarkable reduction of HBV infection and production. Based on these novel findings, we hypothesize that apoE is incorporated into HBV virions and plays important roles in HBV infection and morphogenesis in vivo. The overall goal of this application is to determine the role and underlying molecular mechanisms of apoE in the promotion of HBV infection and morphogenesis in cell culture and in vivo. Our specific aims are: 1) to determine the importance of apoE in the infection and morphogenesis of clinical HBV isolates; 2) to determine apoE-binding receptors and apoE-receptor interactions important for efficient HBV infection; and 3) to illustrate the underlying molecular mechanism of apoE-mediated promotion of HBV morphogenesis. The successful completion of this application will result in a paradigm change regarding the roles of cellular proteins in HBV infection and morphogenesis. The outcomes of our studies will also provide novel molecular targets for discovery and development of antiviral drugs towards the ultimate elimination of HBV infection.