Formation of hepatitis B virus covalently closed circular DNA: Removal of genome-linked protein
Formation of hepatitis B virus covalently closed circular DNA: Removal of genome-linked protein
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DOI：
10.1128/jvi.02721-06
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发表时间：
2007-06-01
影响因子：
5.4
通讯作者：
Hu, Jianming
中科院分区：
文献类型：
--
作者：
Gao, Weifan;Hu, Jianming
乙肝病毒包含一个小的、部分双链的、松弛的环状(RC)DNA基因组。RC DNA需要转化为共价闭合环(CCC)DNA，它是所有病毒RNA转录的模板。作为了解CCC DNA形成的第一步，我们分析了可能参与CCC DNA形成的病毒和宿主因素，使用瞬时和稳定的HBVDNA转染法，以及相关的禽类肝炎病毒，鸭乙肝病毒(DHBV)。我们的结果表明，在肝癌细胞中形成的HBVccDNA主要来自于具有精确连接序列的RC DNA。与DHBVccDNA的形成不同，在培养细胞中，伴随着一种RCDNA的积累，从该RCDNA中去除了共价连接的病毒逆转录酶(RT)蛋白(无蛋白或PF-RCDNA)。此外，虽然包膜缺陷导致DHBVCCC DNA形成增加，但主要导致Pf-RC增加，但不引起HBVccDNA的增加，这表明包膜蛋白(S)可能负调控CCPDNA形成的一个步骤，该步骤先于去蛋白在HBVDNA和DHBVDNA的形成。有趣的是，与RT连锁的RC DNA相比，PF-RC DNA几乎全部含有成熟的正链DNA，这表明RT蛋白优先从成熟的RC DNA中移除。
Hepatitis B virus (HBV) contains a small, partially double-stranded, relaxed circular (RC) DNA genome. RC DNA needs to be converted to covalently closed circular (CCC) DNA, which serves as the template for all viral RNA transcription. As a first step toward understanding how CCC DNA is formed, we analyzed the viral and host factors that may be involved in CCC DNA formation, using transient and stable DNA transfections of HBV and the related avian hepadnavirus, duck hepatitis B virus (DHBV). Our results show that HBV CCC DNA formed in hepatoma cells was derived predominantly from RC DNA with a precise junction sequence. In contrast to that of DHBV, HBV CCC DNA formation in cultured cells was accompanied by the accumulation of a RC DNA species from which the covalently attached viral reverse transcriptase (RT) protein was removed (protein-free or PF-RC DNA). Furthermore, whereas envelope deficiency led to increased CCC DNA formation in DHBV, it resulted mainly in increased PF-RC, but not CCC, DNA in HBV, suggesting that the envelope protein(s) may negatively regulate a step in CCC DNA formation that precedes deproteination in both HBV and DHBV. Interestingly, PF-RC DNA, in contrast to RT-linked RC DNA, contained, almost exclusively, mature plus-strand DNA, suggesting that the RT protein was removed preferentially from mature RC DNA.