Two core promotor mutations identified in a hepatitis B virus strain associated with fulminant hepatitis result in enhanced viral replication
Two core promotor mutations identified in a hepatitis B virus strain associated with fulminant hepatitis result in enhanced viral replication
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DOI：
10.1172/jci119037
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发表时间：
1996-11-15
影响因子：
15.9
通讯作者：
Liang, TJ
中科院分区：
文献类型：
--
作者：
Baumert, TF;Rogers, SA;Liang, TJ
病毒突变与乙型肝炎病毒（HBV）生物表型的改变有关。我们最近克隆并测序了与暴发性肝炎爆发相关的 HBV 毒株（FH 毒株）的病毒基因组。 FH菌株在所有基因组区域中含有大量突变，其功能特征是更有效地衣壳化前基因组RNA，从而导致高度增强的复制。为了定义增强复制的责任突变，我们通过寡核苷酸定向诱变将FH菌株的单个突变引入野生型构建体中。病毒复制分析表明，FH菌株中的两个相邻突变 HBV核心启动子（核苷酸1768处的C到T和核苷酸1770处的T到A）导致高水平复制，与FH菌株类似，该突变体表现出前基因组RNA衣壳化增强的表型。衣壳化验中的功能研究表明，所识别的突变导致前基因组 RNA 转录略有增加（2 至 3 倍），并且病毒衣壳化的主要转录无关增强（> 10 倍）。我们的结果表明，HBV 核心启动子区域中的两个相邻突变负责 FH 菌株复制的增强。这两个突变位于先前描述的衣壳化之外 信号、核心和聚合酶多肽似乎影响了与病毒衣壳化有关的新遗传元件。
Viral mutations have been implicated in alteration of the biological phenotype of hepatitis B virus (HBV). We recently cloned and sequenced the viral genome of an HBV strain associated with an outbreak of fulminant hepatitis (FH strain). The FH strain contained numerous mutations in all genomic regions and was functionally characterized by a more efficient encapsidation of pregenomic RNA leading to highly enhanced replication, To define the responsible mutation(s) for the enhanced replication, we introduced individual mutations of the FH strain into a wild-type construct by oligonucleotide-directed mutagenesis, Analysis of viral replication showed that two adjacent mutations in the HBV core promotor (C to T at nucleotide 1768 and T to A at nucleotide 1770) led to high level replication, Similar to the FH strain, this mutant displayed the phenotype of enhanced encapsidation of pregenomic RNA. Functional studies in an encapsidation assay demonstrated that the identified mutations resulted in a minor increase of pregenomic RNA transcription (two- to threefold) and a major transcription-independent enhancement (> 10-fold) of viral encapsidation, Our results demonstrate that the two adjacent mutations in the HBV core promotor region are responsible for the enhanced replication of the FH strain, These two mutations, outside the previously described encapsidation signal, core, and polymerase polypeptides, appeared to affect a novel genetic element involved in viral encapsidation.