'IMMATURE SECRETION' VARIANTS OF HUMAN HEPATITIS B VIRUS

人类乙型肝炎病毒的“不成熟分泌”变种

• 批准号: 6038548
• 负责人: CHIAHO SHIH
• 金额: $ 20.12万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-04 至 2005-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6038548
• 关键词: Hepadnaviridae; clinical research; gene mutation; genetic strain; hepatitis B antigens; hepatitis B virus group; human subject; marmots; mutant; nucleocapsid; phenotype; tissue /cell culture; virion; virus envelope; virus genetics; virus replication

Our long-term goal is to understand the pathobiology of viral hepatitis. Hepatitis B virus (HBV) is the 4th most common infectious agent in humans worldwide. Chronic infection with HBV is tightly associated with the development of liver cancer. The mechanism of how HBV chronic infection is established and its pathogenesis remains to be fully explored. Recently, there has been increasing evidence that HBV chronicity may be influenced by the presence of genetic variants that evolve in patients as liver disease progresses. Since the invention of polymerase chain reaction technology, many HBV sequence variants have been reported. However, a common frustration in the research of HBV variants is that the majority of these reported sequence variants has no known functional significance and does not exhibit a strong phenotype distinctively different from the wild type virus. The most frequent missense mutation found in the HBV core antigen occurs at codon 97 in chronic carriers worldwide (in 83 percent hepatoma patients). Our recent functional characterization of this mutant uncovered a novel and strong phenotype, dubbed an "immature secretion" phenotype. Unlike wild type HBV, the secreted Dane particles of codon 97 mutants contain predominantly the immature form (lower molecular weight) of the HBV DNA genome. In this application, we propose 1) to extend our observation of the "immature secretion" phenomenon from tissue culture to patients and animal models. We also attempt to extend the "immature secretion" phenotype to other viral subtypes prevalent in different geographic locations. 2) to investigate the mechanism of "immature secretion" by both genetic and biochemical approaches. One of the several hypotheses to be tested is that "immature secretion" could be caused by hyper-efficient interactions between wild type envelope and mutant core proteins. 3) Finally, we will compare the infectivity of the highly frequent codon 97 mutants and wild type HBV via in vitro infection assays. Successful completion of this work will help understand the fundamental rules governing HBV morphogenesis and virion secretion, in addition to the important implications for chronic viral hepatitis as well as many other chronic progressive viral diseases.

我们的长期目标是了解病毒性肝炎的病理学。 乙型肝炎病毒 (HBV) 是全世界人类第四大最常见的传染源。 慢性乙型肝炎病毒感染与肝癌的发生密切相关。 HBV慢性感染的机制及其发病机制仍有待充分探讨。 最近，越来越多的证据表明，随着肝病的进展，患者体内出现的基因变异可能会影响乙型肝炎的慢性化。 自从聚合酶链式反应技术发明以来，已经报道了许多HBV序列变异体。 然而，HBV 变体研究中常见的一个挫折是，大多数报道的序列变体没有已知的功能意义，并且没有表现出与野生型病毒明显不同的强烈表型。 在全世界慢性携带者中（83% 的肝癌患者），HBV 核心抗原中最常见的错义突变发生在密码子 97 处。 我们最近对该突变体的功能表征发现了一种新颖且强大的表型，称为“不成熟分泌”表型。 与野生型 HBV 不同，密码子 97 突变体分泌的 Dane 颗粒主要含有 HBV DNA 基因组的未成熟形式（较低分子量）。 在此应用中，我们建议1）将我们对“不成熟分泌”现象的观察从组织培养扩展到患者和动物模型。 我们还尝试将“不成熟分泌”表型扩展到不同地理位置流行的其他病毒亚型。 2）通过遗传和生化方法研究“不成熟分泌”的机制。 要测试的几个假设之一是“不成熟分泌”可能是由野生型包膜蛋白和突变核心蛋白之间的超高效相互作用引起的。 3）最后，我们将通过体外感染测定比较高频密码子97突变体和野生型HBV的感染性。 成功完成这项工作将有助于了解控制 HBV 形态发生和病毒颗粒分泌的基本规则，以及对慢性病毒性肝炎以及许多其他慢性进行性病毒性疾病的重要影响。