HDV spread during chronic infection as a novel target for antiviral intervention

慢性感染期间 HDV 传播作为抗病毒干预的新目标

• 批准号: 8516456
• 负责人: Severin O Gudima
• 金额: $ 21.29万
• 依托单位: UNIVERSITY OF KANSAS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8516456
• 关键词: Academy; Acute; American; Animals; Anti-HIV Agents; Antineoplastic Agents; Antiviral Agents; Attention; Basic Science; Binding; Biological Assay; Brazil; Cells; China; Chronic; Chronic Hepatitis; Chronic Hepatitis B; Country; Data; Disadvantaged; Drug Targeting; Elements; Europe; Event; Famciclovir; Future; Genome; Goals; Health; Helper Viruses; Hepadnaviridae; Hepatitis B; Hepatitis B Vaccines; Hepatitis B Virus; Hepatitis C; Hepatitis Delta Virus; Hepatitis delta Antigens; Hepatocyte; Human; Immigrant; Immune; In Vitro; Incidence; India; Individual; Infection; Institute of Medicine (U.S.); Interferon-alpha; Interferons; Intervention; Iran; Lamivudine; Lead; Life Cycle Stages; Liver; Liver diseases; Maintenance; Malignant neoplasm of liver; Measures; Medical; Messenger RNA; Modeling; Mongolia; Mutation; Nature; Open Reading Frames; Pan Genus; Pathogenesis; Peptides; Pharmaceutical Preparations; Predictive Factor; Prevention approach; Primary carcinoma of the liver cells; Production; Replication Initiation; Reporting; Research; Resistance; Risk; Risk Factors; Role; South American; Staging; Tajikistan; Telbivudine; Tenofovir; Testing; Therapeutic; Time; Transcript; Travel; Tunisia; United States; Vietnam; Viral Proteins; Virion; Virus; Virus Assembly; Virus Diseases; Virus Receptors; Virus Replication; Work; adefovir; analog; anti-hepatitis B; base; entecavir; env Gene Products; farnesylation; hepatitis B virus L protein; hepatitis B virus P protein; improved; in vivo; inhibitor/antagonist; migration; mortality; mutant; novel; pathogen; receptor binding; reconstitution; response; viral DNA; viral RNA; virus envelope

DESCRIPTION (provided by applicant): Chronic hepatitis B virus (HBV) infection is the main cause of hepatocellular carcinoma (HCC) worldwide and is responsible for 50-80% of all HCC cases. Of the 400 million current chronic HBV carriers, about 65 million will die from an advanced liver disease or HCC. Concomitant infection with hepatitis delta virus (HDV) usually enhances liver pathogenesis. HDV, a subviral agent of HBV, always co-exists with its helper HBV in nature and uses HBV envelope proteins to form the virions and infect hepatocytes via HBV receptor(s). The number of chronic HDV carriers worldwide is about 20 million. HDV is a significant human pathogen. Chronic carriers of HBV/HDV have 3-fold increased risk of HCC incidence, and develop HCC approximately 14 years earlier than carriers of HBV only. Persistent HDV replication is a predictive factor for liver-associated mortality. Currently, there s no therapy against HDV, and a number of anti-HBV drugs do not block HDV infection. Carriers of HBV and HDV cannot be helped by HBV vaccine and desperately need novel targets for medical interventions and new treatments. We propose to exploit the uniqueness of the mechanism of chronic HDV infection in a search for a novel target for antiviral intervention. Briefly, despite studies suggesting that cell-to-cell spread of a helper hepadnavirus (HBV) during chronic infection is an unlikely event, the occurrence of the spread of either HBV or HDV during chronic infections was neither demonstrated nor disproved. However, our analysis of HDV mRNA in transfected cells and in the liver of transiently infected animal suggests that in absence of the spread, HDV genomes accumulate mutations in the open reading frame (ORF) for delta antigen (?Ag) (the only HDV protein and is essential for HDV replication) that preclude self-sustained HDV replication. Therefore, this application will test the hypothesis that HDV must rely on continuous cell-to-cell spread to maintain chronic infection. Our goal is to determine if HDV spread is a valid novel target for intervention against chronic HDV infection. We will conduct in vitro and in vivo HDV infections either in the presence or in the absence of the spread. To analyze three critical aspects of HDV spread, we propose to: (i) assay the ?Ag ORF for mutations that make ?Ag unable to support HDV replication (Aim 1), (ii) measure the replication capacity of HDV genomes (Aim 1), and (iii) compare infectivities of HDV virions early and late in chronic infection (Aim 2). We will determine for the first time whether, in infected hepatocytes in the absence of spread, HDV genomes lose the ability for self-sustained replication due to mutations in ?Ag ORF, and whether ongoing spread selects against the genomes encoding non-functional ?Ags. Overall, this study will greatly advance our understanding of the mechanism of chronic HBV/HDV infection, and will likely (i) identify HDV spread as a factor of pathogenesis and HCC risk, and (ii) facilitate the use of inhibitors of the assembly and entry as novel antivirals for HDV carriers. Furthermore, if HBV spread during chronic infection is demonstrated, virus entry inhibitors will work for HBV carriers regardless of HBV mutants resistant to current anti-HBV drugs.

描述（由申请人提供）：慢性B型肝炎病毒（HBV）感染是全球肝细胞癌（HCC）的主要原因，占所有HCC病例的50-80%。在目前的4亿慢性HBV携带者中，约有6500万人将死于晚期肝病或HCC。伴随感染丁型肝炎病毒（HDV）通常会增强肝脏发病机制。HDV是HBV的一种亚病毒因子，在自然界中总是与其辅助HBV共存，并利用HBV包膜蛋白形成病毒体并通过HBV受体感染肝细胞。全球慢性HDV携带者的数量约为2000万。HDV是一种重要的人类病原体。HBV/HDV慢性携带者发生HCC的风险增加3倍，并且比仅HBV携带者早发生HCC约14年。持续HDV复制是肝脏相关死亡率的预测因素。目前，没有针对HDV的治疗方法，并且许多抗HBV药物不能阻断HDV感染。HBV和HDV携带者不能通过HBV疫苗得到帮助，迫切需要新的药物干预和新的治疗靶点。我们建议利用慢性HDV感染机制的独特性，寻找一种新的抗病毒干预靶点。简而言之，尽管研究表明慢性感染期间辅助嗜肝DNA病毒（HBV）的细胞间传播是不太可能发生的事件，但慢性感染期间HBV或HDV传播的发生既未得到证实也未被反驳。然而，我们对转染细胞和瞬时感染动物肝脏中HDV mRNA的分析表明，在没有传播的情况下，HDV基因组在δ抗原（？Ag）（唯一的HDV蛋白，并且是HDV复制所必需的），其阻止了HDV的自我维持复制。因此，本申请将测试HDV必须依赖于连续的细胞间传播来维持慢性感染的假设。我们的目标是确定HDV传播是否是干预慢性HDV感染的有效新靶点。我们将在存在或不存在传播的情况下进行体外和体内HDV感染。要分析三个关键方面的HDV传播，我们建议：（i）分析？Ag ORF的突变，使？Ag不能支持HDV复制（目的1），（ii）测量HDV基因组的复制能力（目的1），和（iii）比较HDV病毒粒子在慢性感染早期和晚期的感染性（目的2）。我们将第一次确定是否，在感染的肝细胞在没有传播，HDV基因组失去自我维持复制的能力，由于突变？Ag ORF，以及是否正在进行的传播选择对基因组编码的非功能性？艾格斯总的来说，这项研究将大大推进我们对慢性HBV/HDV感染机制的理解，并可能（i）确定HDV传播作为发病机制和HCC风险的一个因素，（ii）促进使用组装和进入抑制剂作为HDV携带者的新型抗病毒药物。此外，如果证实HBV在慢性感染期间传播，则病毒进入抑制剂将对HBV携带者起作用，而不管HBV突变体对当前抗HBV药物的耐药性如何。