The Molecular Mechanism of Antibody Neutralization of Hepatitis C Virus

描述(申请人提供)：丙型肝炎病毒是一种慢性病毒性疾病，感染肝脏。感染通过注射吸毒或受污染的血液制品传播，约80%的感染者成为慢性感染者。慢性丙型肝炎病毒感染与患肝硬变和肝细胞癌的风险增加有关。事实上，丙型肝炎病毒是美国肝移植的主要原因。目前，还没有针对丙型肝炎病毒的疫苗，聚乙二醇化干扰素-？2B和利巴韦林治疗方案仅对约50%的患者有效。由于缺乏小动物模型，而且直到最近，细胞培养适应的病毒，对丙型肝炎病毒感染的免疫反应知之甚少。丙型肝炎病毒包膜-2(E2)在病毒粒子表面表达，被认为在介导病毒附着和进入中起重要作用。在感染的患者中发现了针对E2蛋白的中和抗体，尽管这些抗体的作用机制和它们与之结合的表位仍然知之甚少。进一步了解抗E2抗体是如何中和感染的，并确定重要的中和表位，将为未来丙型肝炎疫苗和新疗法的开发提供一个框架。这项建议的目的是研究针对丙型肝炎病毒E2的抗体中和机制，并确定蛋白中在控制感染方面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批抗E2抗体的中和能力。我们将测试丙型肝炎病毒E2抗体干扰病毒生命周期不同阶段的能力，阻断不同密度的病毒颗粒的感染，并与补体系统相互作用，以增强感染的中和作用。这一目标将使我们能够更好地了解抗体如何发挥作用来限制丙型肝炎病毒感染。在我们的第二个目标中，我们建议研究抗体介导的丙型肝炎病毒E2中和的分子机制。为此，我们计划绘制E2内关键抗体结合残基的图谱，并测试抗体抑制丙型肝炎病毒与CD81结合的能力。这将对病毒进入所必需的E2内的关键残基有更全面的了解。总之，这些目标将使我们能够更好地了解丙型肝炎病毒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产生的靶点。

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.