改建成熟核衣壳和增强全中的病毒粒子的形成共价闭合环状DN

StephenW

J Virol. 2015 Jul 22. pii: JVI.01481-15. [Epub ahead of print]
Alteration of Mature Nucleocapsid and Enhancement of Covalently Closed Circular DNA Formation by Hepatitis B Virus Core Mutants Defective in Complete Virion Formation.Cui X1, Luckenbaugh L1, Bruss V2, Hu J3.
Author information

AbstractAssembly of hepatitis B virus (HBV) begins with packaging of the pregenomic RNA (pgRNA) into immature nucleocapsids (NC), which are converted to mature NCs containing the genomic relaxed circular (RC) DNA as a result of reverse transcription. Mature NCs have two alternative fates, envelopment by viral envelope proteins leading to secretion extracellularly as virions or disassembly (uncoating) to deliver their RC DNA content into the host cell nucleus for conversion to the covalently closed circular (CCC) DNA, the template for viral transcription. How these two alternative fates are regulated remains to be better understood. The NC shell is composed of multiple copies of a single viral protein, the HBV core (HBc) protein. HBc mutations located on the surface of NC have been identified that allow NC maturation but block its envelopment. The potential effects of some of these mutations on NC uncoating and CCC DNA formation have been analyzed by transfecting HBV replication constructs into hepatoma cells. All envelopment-defective HBc mutations tested were competent for CCC DNA formation, indicating that core functions in envelopment and uncoating/nuclear delivery of RC DNA were genetically separable. Some of the envelopment-defective HBc mutations were found to alter specifically the integrity of mature, but not immature, NCs such that RC DNA became susceptible to nuclease digestion. Furthermore, CCC DNA formation could be enhanced by NC surface mutations that did or didn't significantly affect mature NC integrity, indicating that the NC surface residues may be closely involved in NC uncoating and/or nuclear delivery of RC DNA.
IMPORTANCE: Hepatitis B virus (HBV) infection is a major health issue worldwide. HBV assembly begins with the packaging into immature nucleocapsids (NCs) of a viral RNA pregenome, which is converted to the DNA genome in mature NCs. Mature NCs are then selected for envelopment and secretion as complete virion particles, or alternatively, can deliver their DNA to host cell nucleus to maintain the viral genome as nuclear episomes, which are the basis for virus persistence. Previous studies have identified mutations on the capsid surface that selectively block NC envelopment without affecting NC maturation. We have now discovered that some of these same mutations result in preferential alteration of mature NCs and increased viral nuclear episomes. These findings provide important new insights into the regulation of the two alternative fates of mature NCs and suggest new ways to perturb viral persistence by manipulating levels of viral nuclear episomes.
Copyright © 2015, American Society for Microbiology. All Rights Reserved.

StephenW

病毒学杂志。 2015年22月PII：JVI.01481-15。 [打印EPUB的提前]
改建成熟核衣壳和增强全中的病毒粒子的形成共价闭合环状DNA形成的乙肝病毒核心突变体有缺陷的。
崔X1，Luckenbaugh L1，Bruss V2，胡J3。
作者信息
抽象

乙型肝炎病毒（HBV）的装配开始于前基因组RNA（pgRNA）为未成熟的核衣壳（NC），它被转换为成熟含有基因组松弛环状（RC）的DNA作为反转录的结果NC的包装。成熟的NC有两个备选的命运，包络由病毒包膜蛋白导致分泌细胞外的病毒体或拆卸（脱壳），以提供他们的RC DNA含量到宿主细胞核以转换为共价闭合环状（CCC）的DNA，病毒模板转录。如何将这些两种替代命运进行调节仍然可以更好地理解。数控外壳由单一的病毒蛋白，HBV核心（HBC）蛋白质的多个拷贝。位于NC的表面上的HBc突变已经确定，允许NC成熟，但阻断其包围。一些数控脱壳和CCC的DNA形成这些突变的潜在影响已通过转染HBV复制构造成肝癌细胞进行分析。所有包络缺陷的HBc突变试验是胜任CCC DNA的形成，表明在包络和RC的DNA脱壳/核运载的核心功能是基因分离。某些包封缺陷的HBc突变被发现改变特异性的成熟的完整性，但不不成熟，NC的使得RC的DNA成为易受核酸消化。此外，CCC DNA的形成可通过数控表面突变，或并无显著影响成熟数控完整性，表明NC-表面残基可以被密切参与的NC脱壳和/或RC的DNA核递送来增强。
重要性：

乙型肝炎病毒（HBV）感染是世界范围内的主要健康问题。 HBV的装配开始于病毒RNA前基因组，将其转化为DNA基因组中成熟NC的包装为未成熟的核衣壳（NCS）。成熟的NC然后选择用于包络和分泌作为完整病毒颗粒，或可替代地，可以提供他们的DNA到宿主细胞核保持病毒基因组作为核附加体，这是基础病毒的持久性。以前的研究已经确定在衣壳表面突变，选择性阻断数控包络在不影响NC成熟。现在我们已经发现，其中的一些相同突变导致成熟的NC和增加的病毒核附加体优先改变。这些发现提供了重要的新见解的成熟网络控制系统的两个备选命运的调控，并提出新的方法通过操纵病毒核游离体水平扰乱病毒的持久性。

版权所有©2015年，美国微生物学会。版权所有。