'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: 6497951
• 负责人: CHIAHO SHIH
• 金额: $ 21.72万
• 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/6497951
• 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生物学。 B型肝炎病毒（HBV）是世界范围内人类第四大常见传染源。 慢性HBV感染与肝癌的发生密切相关。 HBV慢性感染的形成机制及其发病机制仍有待深入研究。 最近，越来越多的证据表明，随着肝病的进展，HBV慢性化可能会受到患者体内遗传变异的影响。 自从聚合酶链反应技术发明以来，已经报道了许多HBV序列变异。 然而，在HBV变异体的研究中的一个常见的挫折是，这些报道的序列变异体中的大多数没有已知的功能意义，并且没有表现出明显不同于野生型病毒的强表型。 在HBV核心抗原中发现的最常见的错义突变发生在全世界慢性携带者（83%的肝癌患者）的密码子97处。 我们最近对这种突变体的功能表征发现了一种新的和强的表型，称为“不成熟分泌”表型。 与野生型HBV不同，密码子97突变体的分泌型Dane颗粒主要含有HBV DNA基因组的未成熟形式（较低分子量）。 在本申请中，我们提出1）将我们对组织培养中“未成熟分泌物”现象的观察扩展到患者和动物模型。 我们还试图将“未成熟分泌物”表型扩展到不同地理位置流行的其他病毒亚型。 2)从遗传学和生物化学两个方面探讨“不成熟分泌”的机制。 待测试的几个假设之一是，“不成熟分泌”可能是由野生型包膜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试验比较高频密码子97突变体和野生型HBV的感染性。 这项工作的成功完成将有助于了解HBV形态发生和病毒体分泌的基本规则，以及对慢性病毒性肝炎和许多其他慢性进行性病毒性疾病的重要意义。