The Molecular Mechanism of Antibody Neutralization of Hepatitis C Virus

描述（由申请人提供）：丙型肝炎病毒是一种感染肝脏的慢性病毒性疾病。感染是通过注射毒品或受污染的血液制品传播的，大约80%的感染者会变成慢性感染。慢性HCV感染与肝硬化和肝细胞癌的风险增加有关。事实上，HCV是美国肝移植的主要原因。目前，没有HCV疫苗和治疗方案，聚乙二醇干扰素？2b和利巴韦林，仅在~50%的患者中有效。由于缺乏小动物模型，直到最近，细胞培养适应病毒，对HCV感染的免疫应答知之甚少。HCV包膜蛋白-2（E2）表达于病毒粒子表面，被认为在介导病毒附着和进入中起重要作用。在感染患者中发现了针对E2蛋白的中和抗体，尽管这些抗体的作用机制和它们结合的表位仍然知之甚少。进一步了解抗E2抗体如何中和感染和鉴定重要的中和表位将为未来开发抗HCV疫苗和新疗法提供框架。本提案的目的是研究针对HCV E2的抗体中和机制，并确定蛋白质内对控制感染至关重要的抗体结合区域。为了实现这一目标，我们提出了两个具体目标。在第一个目标中，我们建议在体外测试一大组抗E2抗体的中和能力。我们将测试HCV E2抗体干扰病毒生命周期的不同阶段、阻断不同密度的病毒颗粒感染以及与补体系统相互作用以增强感染中和的能力。这一目标将使我们能够更好地了解抗体如何限制HCV感染。在我们的第二个目标中，我们建议研究抗体介导的HCV E2中和的分子机制。在这个目标中，我们计划映射E2内的关键抗体结合残基，并测试抗体抑制HCV与CD 81结合的能力。这将提供一个更彻底的了解E2内的关键残基是必要的病毒进入。总之，这些目标将使我们能够更好地了解HCV中和抗体如何抑制感染，以及特定的病毒表位是否可以用作疫苗开发或新疗法的靶点。 公共卫生相关性：丙型肝炎病毒是一种血液传播的病原体，在约80%的感染个体中导致慢性疾病，并与肝硬化和肝细胞癌的风险增加相关。目前还没有针对HCV的疫苗，可用的治疗方法仅对约50%的患者有效。我们打算研究抗体提供保护免受HCV感染的机制，以更好地为疫苗和治疗开发提供信息。

DESCRIPTION (provided by applicant): Hepatitis C virus is a chronic, viral disease that infects the liver. Infection is transmitted by injection drug use or contaminated blood products, and approximately 80% of infected individuals become chronically infected. Chronic HCV infection is associated with an increased risk of liver cirrhosis and hepatocellular carcinoma. Indeed, HCV is the leading cause of liver transplantation in the United States. Currently, there is no vaccine for HCV and the treatment regimen, pegylated Interferon-?2b and ribavirin, is only effective in ~50% of patients. Due to a lack of small animal model and, until recently, a cell culture adapted virus, little is known about the immune response against HCV infection. HCV Envelope-2 (E2) is expressed on the surface of the virion and is thought to be important in mediating viral attachment and entry. Neutralizing antibodies against the E2 protein are found in infected patients, although the mechanisms by which these antibodies act and the epitopes to which they bind remains poorly understood. An improved understanding of how anti-E2 antibodies neutralize infection and identification of the important neutralizing epitopes would provide a framework for the future development of vaccines and novel therapeutics against HCV. The objective of this proposal is to study the mechanism of antibody neutralization directed against HCV E2 and to identify the antibody binding regions within the protein that are important in controlling infection. To achieve this objective, we propose two specific aims. In the first aim we propose to test the neutralization capabilities of a large panel of anti-E2 antibodies in vitro. We will test the ability of HCV E2 antibodies to interfere with different phases of the viral life cycle, to block infection of viral particles of different densities, and to interact with the complement system to enhance neutralization of infection. This aim will enable us to better understand how antibodies function to limit HCV infection. In our second aim, we propose to investigate the molecular mechanism of antibody-mediated neutralization of HCV E2. In this aim we plan to map the critical antibody binding residues within E2 and to test antibodies for their ability to inhibit HCV binding to CD81. This will provide a more thorough understanding of the critical residues within E2 that are necessary for viral entry. Together, these aims will allow us to generate a better understanding of how HCV neutralizing antibodies inhibit infection and whether specific viral epitopes can be used as targets for vaccine development or the generation of novel therapeutics. PUBLIC HEALTH RELEVANCE: Hepatitis C Virus is a blood born pathogen that results in chronic disease in ~80% of infected individuals and is associated with an increased risk of cirrhosis and hepatocellular carcinoma. Currently there is no vaccine for HCV and the available treatment is only effective in ~50% of patients. We intend to study the mechanism by which antibodies provide protection from HCV infection to better inform vaccine and therapeutic development.