Mechanisms of Hepadnavirus Assembly and Replication

B型肝炎病毒（HBV）是慢性病毒性肝炎的主要病因，其显著增加肝脏损害的风险。 癌症和其他终末期肝病如肝硬化。HBV属于嗜肝DNA病毒科， 具有小DNA基因组并通过RNA中间体复制的副逆转录病毒（ 前基因组RNA或pgRNA）通过独特的逆转录途径。嗜肝DNA病毒最初组装 由衣壳蛋白的多个拷贝组成的未成熟核衣壳（NC），和包装的 pgRNA和病毒包裹的逆转录酶（RT）。不成熟的NC经历了一个 成熟，由此pgRNA被转化为特征性的部分双链（OS）的松弛环状结构。 (RC)通过RT介导的逆转录进行DNA。然后将含有RC DNA的成熟NC选择性地 被病毒包膜（表面）蛋白包被并作为病毒粒子分泌到细胞外。利用最近 建立无细胞和细胞培养系统和新开发的方法和模型，我们提出（1） 确定NC内阻断或触发NC释放的核酸的性质;（2）确定NC内阻断或触发NC释放的核酸的性质;（3）确定NC内阻断或触发NC释放的核酸的性质;（4）确定NC内阻断或触发NC释放的核酸的性质;（5）确定NC内阻断或触发NC释放的核酸的性质;（6）确定NC内阻断或触发NC释放的核酸的性质;（7）确定NC内阻断或触发NC释放的核酸的性质;（8）确定NC内阻断或触发NC释放的核酸的性质;（9）确定NC内阻断或触发NC释放的核酸的性质;（9）确定NC内阻断或触发NC释放的核酸的性质;（10）确定NC内阻断或触发NC释放的核酸的性质。 与成熟相关的NC结构变化及其在NC发育中的作用;（3）确定NC发育的 宿主因子在调节选择性NC表达中的作用。这些经修订的具体目标源自 原申请中提出的具体目标3的三个子目标。这些研究是选择 由于这些项目有可能在两年时间内顺利完成， 2009年美国复苏和再投资法案。而且，它们仍然构成了一个连贯和健全的 项目独立于原始申请的具体目标1和2。分子的阐明 选择性NC治疗的基础、病毒和宿主因素不仅提供重要的 深入了解嗜肝DNA病毒复制和病毒-宿主相互作用的机制，但也可能促进 针对这些因素开发新的有效的抗HBV策略。

Hepatitis B virus (HBV) is a major cause of chronic viral hepatitis that increases dramatically the risk of liver cancer and other end-stage liver diseases such as cirrhosis. HBV belongs to the Hepadnaviridae, a family of para-retroviruses that have a small DNA genome and replicate through an RNA intermediate (the pregenomic RNA, or pgRNA), by a unique reverse transcription pathway. Hepadnaviruses initially assemble an immature nucleocapsid (NC) composed of multiple copies of the capsid protein, and the packaged pgRNA and the virally encQded reverse transcriptase (RT). The immature NC undergoes a process of maturation whereby pgRNA is converted to the characteristic, partially double stranded (OS), relaxed circular (RC) DNA by RT-mediated reverse transcription. The RC DNA-containing, mature NC is then selectively enveloped with the viral envelope (surface) proteins and secreted extracellularly as virions. Using recently established cell-free and cell culture systems and newly developed approaches and models, we propose (1) to determine the nature of nucleic acid within NC that blocks or triggers NC envelopment; (2) to determine the maturation-associated NC structural changes and their role in NC envelopment; and (3) to determine the role of host factors in regulating selective NC envelopment. These Revised Specific Aims are derived from the three sUb-aims of Specific Aim 3 as proposed in the original application. These stUdies are selected because of their likelihood for successful completion within the two year time-frame supported by the the American Recovery and Reinvestment Act of 2009 funding. Also, they still constitute a coherent and sound project separate from Specific Aims 1 and 2 of the original application. The elucidation of the molecular basis of, and viral and host factors involved in, selective NC envelopment will not only provide important insights into the mechanisms of hepadnavirus replication and virus-host interactions but may also facilitate the development of novel and effective anti-HBV strategies targeted at these factors.