Distinct Viral Lineages from Fish and Amphibians Reveal the Complex Evolutionary History of Hepadnaviruses
Distinct Viral Lineages from Fish and Amphibians Reveal the Complex Evolutionary History of Hepadnaviruses
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DOI：
10.1128/jvi.00832-16
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发表时间：
2016-09-01
影响因子：
5.4
通讯作者：
Ng, Terry Fei Fan
中科院分区：
文献类型：
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作者：
Dill, Jennifer A.;Camus, Alvin C.;Ng, Terry Fei Fan
嗜肝DNA病毒（肝炎B病毒[HBV]）是唯一通过RNA中间体的逆转录复制其DNA的动物病毒。直到最近，嗜肝DNA病毒的已知宿主范围仅限于哺乳动物和鸟类。我们获得并分析了第一个两栖动物HBV基因组，以及几个原型鱼HBV，这使得第一个全面的比较基因组分析嗜肝DNA病毒从四类脊椎动物。通过内部病毒宏基因组测序表征蓝鳃病毒嗜肝DNA病毒（BGHBV）。非洲慈鲷嗜肝DNA病毒（ACHBV）和西藏青蛙嗜肝DNA病毒（TFHBV）是使用全基因组鸟枪和转录组鸟枪组装数据库的计算机分析发现的。残基的衣壳（核心）蛋白，指定的基序I，II和III的疏水性基础，是高度保守的，这表明适当的衣壳折叠的结构限制是关键的衣壳蛋白进化。所有脊椎动物HBV的表面蛋白含有相似的预测膜拓扑结构，其特征在于三个跨膜结构域。最引人注目的是，BGHBV，ACHBV，和以前描述的白色吸盘嗜肝DNA病毒没有形成一个鱼的特异性单系组在所有三个嗜肝DNA病毒基因的系统发育分析。值得注意的是，BGHBV与哺乳动物嗜肝DNA病毒更密切相关，表明跨物种传播事件在病毒进化中发挥了重要作用。在TFHBV中也观察到跨种属传播的证据。因此，这些数据表明，嗜肝DNA病毒的进化史比以前实现的更复杂，并结合了数百万年来的病毒-宿主共趋异和宿主物种jumping. IMPORTANCEHepadnaviruses是负责重大疾病的人类（肝炎B病毒），并已报告从各种脊椎动物作为外源性和内源性病毒。我们报告了一种来自鱼类的新型嗜肝DNA病毒的全长基因组和第一个来自两栖动物的嗜肝DNA病毒基因组。从蓝鳃鱼中取样的新型鱼类嗜肝DNA病毒与哺乳动物嗜肝DNA病毒的关系比与其他鱼类病毒的关系更密切。这种系统发育模式表明，虽然嗜肝DNA病毒可能与脊椎动物有数亿年的关系，但它们也具有跨越广泛系统发育距离的物种特征。
Hepadnaviruses (hepatitis B viruses [HBVs]) are the only animal viruses that replicate their DNA by reverse transcription of an RNA intermediate. Until recently, the known host range of hepadnaviruses was limited to mammals and birds. We obtained and analyzed the first amphibian HBV genome, as well as several prototype fish HBVs, which allow the first comprehensive comparative genomic analysis of hepadnaviruses from four classes of vertebrates. Bluegill hepadnavirus (BGHBV) was characterized from in-house viral metagenomic sequencing. The African cichlid hepadnavirus (ACHBV) and the Tibetan frog hepadnavirus (TFHBV) were discovered using in silico analyses of the whole-genome shotgun and transcriptome shotgun assembly databases. Residues in the hydrophobic base of the capsid (core) proteins, designated motifs I, II, and III, are highly conserved, suggesting that structural constraints for proper capsid folding are key to capsid protein evolution. Surface proteins in all vertebrate HBVs contain similar predicted membrane topologies, characterized by three transmembrane domains. Most striking was the fact that BGHBV, ACHBV, and the previously described white sucker hepadnavirus did not form a fish-specific monophyletic group in the phylogenetic analysis of all three hepadnaviral genes. Notably, BGHBV was more closely related to the mammalian hepadnaviruses, indicating that cross-species transmission events have played a major role in viral evolution. Evidence of cross-species transmission was also observed with TFHBV. Hence, these data indicate that the evolutionary history of the hepadnaviruses is more complex than previously realized and combines both virus-host codivergence over millions of years and host species jumping.IMPORTANCEHepadnaviruses are responsible for significant disease in humans (hepatitis B virus) and have been reported from a diverse range of vertebrates as both exogenous and endogenous viruses. We report the full-length genome of a novel hepadnavirus from a fish and the first hepadnavirus genome from an amphibian. The novel fish hepadnavirus, sampled from bluegills, was more closely related to mammalian hepadnaviruses than to other fish viruses. This phylogenetic pattern reveals that, although hepadnaviruses have likely been associated with vertebrates for hundreds of millions of years, they have also been characterized by species jumping across wide phylogenetic distances.