Hepatitis B virus nucleocapsid envelopment does not occur without genomic DNA synthesis
Hepatitis B virus nucleocapsid envelopment does not occur without genomic DNA synthesis
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DOI：
10.1128/jvi.70.7.4269-4274.1996
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发表时间：
1996-07-01
影响因子：
5.4
通讯作者：
Bruss, V
中科院分区：
文献类型：
--
作者：
Gerelsaikhan, T;Tavis, JE;Bruss, V
有包膜的B型肝炎病毒（HBV）的装配是通过RNA前基因组和病毒逆转录酶-DNA聚合酶包装到核衣壳中来启动的。然后前基因组逆转录成单链负极性DNA，其随后复制成双链DNA。所有的复制中间体都可以在感染的肝脏内的衣壳中观察到，但是在分泌的病毒体中只发现含有部分双链DNA的相对成熟的核衣壳。这一观察结果表明，成熟的衣壳内的基因组是所需的复制和分泌，我们表明，细胞内的核衣壳和分泌的病毒粒子之间的复制中间体的差异分布也可观察到在人肝癌细胞转染野生型HBV基因组。然而，当它们由在DNA聚合酶中携带消除所有DNA合成的错义突变的HBV基因组产生时，核衣壳不被包膜或分泌，允许负链DNA合成但不形成双链DNA的聚合酶的RNase H活性缺陷的HBV错义突变体能够形成病毒体样颗粒。这些实验表明，含有前基因组RNA的未成熟核衣壳不能进行扩增，并且衣壳内腔中的负链DNA合成与核衣壳外部出现对其扩增至关重要的信号偶联。
Assembly of the enveloped hepatitis B virus (HBV) is initiated by packaging of the RNA pregenome and the viral reverse transcriptase-DNA polymerase into a nucleocapsid, The pregenome is then reverse transcribed into single-stranded minus-polarity DNA, which is subsequently replicated to double-stranded DNA. All replicative intermediates are observable in capsids within infected liver, but only relatively mature nucleocapsids containing partially double stranded DNA are found in secreted virions. This observation suggests that maturation of the genome within the capsid is required for envelopment and secretion, We show that the differential distribution of replicative intermediates between intracellular nucleocapsids and secreted virions is also observable in human hepatoma cells transfected with wild-type HBV genomes. However, nucleocapsids were not enveloped or secreted when they were produced by an HBV genome carrying a missense mutation in the DNA polymerase that eliminates all DNA synthesis, An HBV missense mutant defective in the RNase H activity of the polymerase which allowed minus-strand DNA synthesis but not formation of double-stranded DNA was able to form virion-like particles. These experiments demonstrate that immature nucleocapsids containing pregenomic RNA are incompetent for envelopment and that minus-strand DNA synthesis in the interior lumen of the capsid is coupled to the appearance of a signal on the exterior of the nucleocapsid that is essential for its envelopment.