Snow Goose Hepatitis B Virus (SGHBV) Envelope and Capsid Proteins Independently Contribute to the Ability of SGHBV To Package Capsids Containing Single-Stranded DNA in Virions
Snow Goose Hepatitis B Virus (SGHBV) Envelope and Capsid Proteins Independently Contribute to the Ability of SGHBV To Package Capsids Containing Single-Stranded DNA in Virions
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DOI：
10.1128/jvi.01694-14
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发表时间：
2014-09-01
影响因子：
5.4
通讯作者：
Loeb, Daniel D.
中科院分区：
文献类型：
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作者：
Greco, Natalie;Hayes, Michael H.;Loeb, Daniel D.
嗜肝DNA病毒选择性地将含有成熟双链DNA（dsDNA）基因组的衣壳包装在病毒体中。雪雁乙型肝炎病毒（Snow Goose Hepatitis B Virus，SGHBV）是目前已知的唯一一种以单链DNA（single stranded DNA，ssDNA）为衣壳的嗜肝DNA病毒。我们发现，复制SGHBV的细胞产生含有ssDNA的病毒粒子与含有成熟dsDNA的病毒粒子一样有效。我们确定SGHBV衣壳和包膜蛋白独立地有助于含有ssDNA的病毒体的产生，其中衣壳蛋白（Cp）做出更大的贡献。我们确定SGHBV Cp的氨基酸残基74和107有助于SGHBV的这一特征。当我们改变鸭B肝炎病毒（DHBV）Cp中的这些残基时，含有未成熟ssDNA的衣壳被包装在病毒粒子中。该结果表明，残基74和107有助于衣壳表面上的“衣壳包装信号”的出现，并在病毒体形成期间与包膜蛋白相互作用。我们还发现，复制SGHBV的细胞比复制DHBV的细胞将它们合成为病毒体的总dsDNA的更大部分包装起来。我们确定SGHBV的包膜蛋白负责SGHBV的这种性质。确定是否SGHBV包膜蛋白的能力，导致形成含有ssDNA的病毒粒子的能力，以支持高水平的病毒粒子生产或如果这两个属性是机械上不同的将提供深入了解病毒粒子morphogenesis.IMPORTANCE细胞复制嗜肝DNA病毒含有细胞质衣壳，包含成熟和不成熟的基因组。然而，只有含有成熟dsDNA基因组的衣壳被包装在病毒体中。目前缺乏对这种现象的机械理解，这对于理解嗜肝DNA病毒的病毒粒子形态发生的过程至关重要。在这项研究中，我们确定了包膜蛋白有助于嗜肝DNA病毒选择性产生含有成熟双链DNA基因组的病毒体的能力。我们的发现揭示了病毒粒子形态发生的机制，并挑战了“衣壳成熟”以及因此衣壳蛋白（Cp）仅负责选择性产生含有成熟dsDNA基因组的病毒粒子的教条。此外，我们鉴定了Cp的氨基酸残基，这些氨基酸残基有助于其引起含有成熟dsDNA基因组的病毒体的选择性产生的能力。对这些残基在选择性分泌中的作用的未来研究将拓宽我们对病毒复制这一知之甚少的方面的理解。
Hepadnaviruses selectively package capsids containing mature double-stranded DNA (dsDNA) genomes in virions. Snow goose hepatitis B virus (SGHBV) is the only known hepadnavirus that packages capsids containing single-stranded DNA (ssDNA) in virions. We found that cells replicating SGHBV produce virions containing ssDNA as efficiently as virions containing mature dsDNA. We determined that SGHBV capsid and envelope proteins independently contribute to the production of virions containing ssDNA, with the capsid protein (Cp) making a larger contribution. We identified that amino acid residues 74 and 107 of SGHBV Cp contribute to this feature of SGHBV. When we changed these residues in duck hepatitis B virus (DHBV) Cp, capsids containing immature ssDNA were packaged in virions. This result suggests that residues 74 and 107 contribute to the appearance of the "capsid packaging signal" on the surface of capsids and interact with the envelope proteins during virion formation. We also found that cells replicating SGHBV package a larger fraction of the total dsDNA they synthesize into virions than do those replicating DHBV. We determined that the SGHBV envelope proteins are responsible for this property of SGHBV. Determining if the ability of SGHBV envelope proteins to cause the formation of virions containing ssDNA is related to its ability to support high levels of virion production or if these two properties are mechanistically distinct will provide insights into virion morphogenesis.IMPORTANCE Cells replicating hepadnaviruses contain cytoplasmic capsids that contain mature and immature genomes. However, only capsids containing mature dsDNA genomes are packaged in virions. A mechanistic understanding of this phenomenon, which is currently lacking, is critical to understanding the process of hepadnaviral virion morphogenesis. In this study, we determined that the envelope proteins contribute to the ability of hepadnaviruses to selectively produce virions containing mature dsDNA genomes. Our finding sheds new light on the mechanisms underlying virion morphogenesis and challenges the dogma that "capsid maturation," and therefore the capsid protein (Cp), is solely responsible for the selective production of virions containing mature dsDNA genomes. Further, we identified amino acid residues of Cp that contribute to its ability to cause the selective production of virions containing mature dsDNA genomes. Future studies on the role of these residues in selective secretion will broaden our understanding of this poorly understood aspect of virus replication.