Role of antibodies in hepatitis E virus infection

抗体在戊型肝炎病毒感染中的作用

基本信息

批准号：
10639161
负责人：
Zongdi Feng
金额：
$ 86.43万
依托单位：
RESEARCH INST NATIONWIDE CHILDREN'S HOSP
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-04-19 至 2028-03-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10639161
关键词：
Acute Hepatitis Affect Antibodies Antibody titer measurement Binding Blood Circulation C-terminal Capsid Capsid Proteins Cell Culture Techniques Cells Chronic Hepatitis Complex Cryoelectron Microscopy Data Effectiveness Endosomes Enteral Feces Glycoengineering Goals Hepatitis E virus Hepatocyte Immune system Immunocompromised Host Immunoglobulin G Individual Infection Knowledge Left Life Cycle Stages Liver Cirrhosis Liver diseases Lysosomes Macaca Mediating Membrane Monoclonal Antibodies Patients Process Publishing RNA Viruses Research Resistance Risk Role Serum Solid Structural Models Structure Surface Testing Therapeutic Therapeutic Effect Vaccinated Vaccination Vaccines Viral Viral Antigens Virion Virus Virus Diseases Work humanized mouse insight liver injury neutralizing antibody neutralizing monoclonal antibodies novel novel strategies organ transplant recipient particle prevent receptor transmission process uptake vaccine-induced antibodies viral transmission

项目摘要

Summary The goal of the proposed study is to better understand the role of antibodies in HEV infection and determine if antibodies can prevent or cure chronic hepatitis E virus (HEV) infection. HEV infections are usually self-limited, but the infections frequently persist when the immune system is compromised and if left untreated, can lead to serious liver disease. HEV exists in two distinct virion forms: naked virions (nHEV) that are shed into feces and mediate virus transmission between hosts, and quasi-enveloped HEV (eHEV) virions that circulate in the bloodstream and mediate virus spread between cells. The eHEV particles lack viral antigens on their surface, thus they are resistant to circulating HEV-specific antibodies. We previously show that eHEV particles enter cells via a novel entry mechanism that involves lysosomal degradation of the viral envelope. Our recent data show that HEV-specific IgG, but not IgM, effectively block eHEV-mediated spread in cell culture. Our central hypothesis is that antibodies neutralize eHEV intracellularly by preventing virus uncoating in the endosome/lysosome where the viral membrane degrades. Antibodies generated by natural HEV infection and vaccination with truncated HEV capsid proteins (CP) are highly protective against HEV infection, while anti-HEV antibody titers are usually low in patients with chronic HEV infection. Thus, antibodies may have the potential to prevent or treat chronic HEV infection. Despite these encouragements, there are several significant roadblocks. First, the C terminus of the HEV CP, which is not present in the current vaccine and the fecal virus, is intact in the eHEV particles. This is important since structural modeling suggests that the presence of the C terminus of CP significantly alters the surface structure of the virion which likely makes vaccine-induced antibodies less effective against eHEV. Second, our recent work indicates that HEV produces a capsid decoy that is secreted from infected cells in a large quantity and interferes with antibody-mediated neutralization. Third, antibody uptake by hepatocytes is an inefficient process. Here we propose to overcome these obstacles. Aim 1 will test the hypothesis that antibodies targeting virions with intact CP will block eHEV-mediated spread more efficiently. We will determine the structure of authentic HEV virions with intact or cleaved CP and assess if antibodies targeting virions with intact CP neutralize eHEV more efficiently. We will also determine if glycoengineered antibodies with enhanced lysosomal targeting neutralize eHEV more efficiently. Aim 2 will test the hypothesis that neutralizing antibodies that do not bind or bind poorly to the decoy will block HEV spread more efficiently. We will also determine the structure of the CP decoy in complex with antibodies by cryo-EM to gain a better understanding of the evasion mechanism by the decoy. The completion of the proposed work will provide novel insights into the role of antibodies in HEV infection and inform strategies to prevent or cure chronic HEV infection.

概括拟议研究的目的是更好地了解抗体在 HEV 感染中的作用并确定是否抗体可以预防或治愈慢性戊型肝炎病毒（HEV）感染。 HEV 感染通常具有自限性，但当免疫系统受损时，感染往往会持续存在，如果不及时治疗，可能会导致严重的肝脏疾病。 HEV 以两种不同的病毒体形式存在：裸露病毒体 (nHEV)，它们会排泄到粪便中；介导宿主之间的病毒传播，以及在宿主体内循环的准包膜 HEV (eHEV) 病毒颗粒血液流动并介导病毒在细胞间传播。 eHEV 颗粒表面缺乏病毒抗原，因此，它们对循环中的 HEV 特异性抗体具有抵抗力。我们之前证明 eHEV 颗粒进入细胞通过一种涉及病毒包膜溶酶体降解的新型进入机制。我们最近的数据显示 HEV 特异性 IgG（而非 IgM）可有效阻止 eHEV 介导的细胞培养传播。我们的中央假设是抗体通过阻止病毒在细胞内脱壳来中和细胞内的 eHEV 病毒膜降解的内体/溶酶体。天然 HEV 感染产生的抗体和接种截短的 HEV 衣壳蛋白 (CP) 对 HEV 感染具有高度保护作用，而抗 HEV 慢性 HEV 感染患者的抗体滴度通常较低。因此，抗体可能有潜力预防或治疗慢性 HEV 感染。尽管有这些鼓励，但仍存在一些重大障碍。首先，当前疫苗和粪便病毒中不存在的HEV CP的C末端在 eHEV 粒子。这很重要，因为结构模型表明 C 末端的存在 CP 显着改变病毒颗粒的表面结构，这可能会降低疫苗诱导的抗体对 eHEV 有效。其次，我们最近的工作表明 HEV 产生一种分泌的衣壳诱饵大量来自受感染细胞并干扰抗体介导的中和。三、抗体摄取肝细胞的作用是一个低效的过程。在此，我们建议克服这些障碍。目标 1 将测试假设针对具有完整 CP 的病毒粒子的抗体将更有效地阻止 eHEV 介导的传播。我们将确定具有完整或切割 CP 的真实 HEV 病毒粒子的结构，并评估抗体是否靶向具有完整 CP 的病毒颗粒可以更有效地中和 eHEV。我们还将确定糖工程抗体是否具有增强的溶酶体靶向更有效地中和 eHEV。目标 2 将检验以下假设：中和不与诱饵结合或结合不良的抗体将更有效地阻止 HEV 传播。我们也会通过冷冻电镜确定 CP 诱饵与抗体复合物的结构，以获得更好的理解诱饵的逃避机制。拟议工作的完成将为以下方面提供新的见解抗体在 HEV 感染中的作用，并为预防或治疗慢性 HEV 感染提供策略。