Hepatitis delta virus RNA encoding the large delta antigen cannot sustain replication due to rapid accumulation of mutations associated with RNA editing.
Hepatitis delta virus RNA encoding the large delta antigen cannot sustain replication due to rapid accumulation of mutations associated with RNA editing.
复制标题
由于与RNA编辑相关的突变快速积累，编码大δ抗原的丁型肝炎病毒RNA无法维持复制。
DOI：
10.1128/jvi.77.22.12048-12056.2003
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发表时间：
2003
影响因子：
5.4
通讯作者：
Lai,MichaelMC
中科院分区：
文献类型：
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作者：
Macnaughton,ThomasB;Li,Yi-Ija;Doughty,AlisonL;Lai,MichaelMC
丁型肝炎病毒（HDV）含有两种RNA（HDV-S和HDV-L），分别编码小和大形式的丁型肝炎抗原（S-和L-HDAg）。HDV-L RNA是在HDV-S RNA的琥珀/W位点发生的RNA编辑事件的结果。RNA编辑必须受到调控，以防止HDV-L RNA在病毒生命周期中过早和过度积累。在本研究中，我们使用RNA转染程序来研究HDV-L和HDV-S RNA的复制能力。虽然HDV-S导致稳健的RNA复制，但HDV-L甚至在转染后6天后也不能复制。HDV-L复制失败不是由于S-HDAg量不足，因为在稳定过表达S-HDAg的细胞系中获得了相同的结果。而且，这不是由于L-HDAg的可能抑制，因为当HDV-L和HDV-S RNA共转染时，HDV-S RNA复制不受影响。此外，当通过定点诱变消除来自HDV-L RNA的L-HDAg表达时，突变体HDV-L RNA也不能复制。出乎意料的是，当每天检查RNA复制的动力学时，发现HDV-L在早期时间点（转染后1至2天）以低水平复制，但随后在稍后的时间点失去这种能力。在转染后第1天对复制的HDV-L RNA的序列分析表明，它经历了多个核苷酸的变化，特别是在HDV RNA复制的推定启动子区域附近的区域。相反，在HDV-S RNA中发现很少的突变。这些结果表明，在琥珀/W位点的编辑触发了一系列额外的突变，这些突变迅速降低了所得HDV基因组的复制效率，从而有助于调节感染细胞中HDV-L RNA的量。他们还解释了为什么尽管病毒粒子中存在HDV-L RNA，但HDV感染早期并未产生L-HDAG。
Hepatitis delta virus (HDV) contains two RNA species (HDV-S and HDV-L), which encode the small and large forms of hepatitis delta antigens (S- and L-HDAg), respectively. HDV-L RNA is a result of an RNA editing event occurring at an amber/W site of HDV-S RNA. RNA editing must be regulated to prevent premature and excessive accumulation of HDV-L RNA in the viral life cycle. In this study, we used an RNA transfection procedure to study the replication abilities of HDV-L and HDV-S RNA. While HDV-S led to robust RNA replication, HDV-L could not replicate even after 6 days following transfection. The failure of HDV-L to replicate was not due to insufficient amounts of S-HDAg, as identical results were obtained in a cell line that stably overexpresses S-HDAg. Also, it was not due to possible inhibition by L-HDAg, as HDV-S RNA replication was not affected when both HDV-L and HDV-S RNA were cotransfected. Further, when L-HDAg expression from HDV-L RNA was abolished by site-directed mutagenesis, the mutant HDV-L RNA also failed to replicate. Unexpectedly, when the kinetics of RNA replication was examined daily, HDV-L was found to replicate at a low level at the early time points (1 to 2 days posttransfection) but then lose this capability at later time points. Sequence analysis of the replicated HDV-L RNA at day 1 posttransfection showed that it had undergone multiple nucleotide changes, particularly in the region near the putative promoter region of HDV RNA replication. In contrast, very few mutations were found in HDV-S RNA. These results suggest that the editing at the amber/W site triggers a series of additional mutations which rapidly reduce the replication efficiency of the resultant HDV genome and thus help regulate the amount of HDV-L RNA in infected cells. They also explain why L-HDAg is not produced early in HDV infection, despite the fact that HDV-L RNA is present in the virion.