Institute of Experimental Pathology (ZMBE), University of Münster, Von-Esmarch-Straße 56, D-48149 Münster, Germany.
Nat Commun. 2013;4:1791. doi: 10.1038/ncomms2798.
Paleovirology involves the identification of ancient endogenous viral elements within eukaryotic genomes. The evolutionary origins of the reverse-transcribing hepatitis B viruses, however, remain elusive, due to the small number of endogenized sequences present in host genomes. Here we report a comprehensively dated genomic record of hepatitis B virus endogenizations that spans bird evolution from >82 to <12.1 million years ago. The oldest virus relic extends over a 99% complete hepatitis B virus genome sequence and constitutes the first discovery of a Mesozoic paleovirus genome. We show that Hepadnaviridae are >63 million years older than previously known and provide direct evidence for coexistence of hepatitis B viruses and birds during the Mesozoic and Cenozoic Eras. Finally, phylogenetic analyses and distribution of hepatitis B virus relics suggest that birds potentially are the ancestral hosts of Hepadnaviridae and mammalian hepatitis B viruses probably emerged after a bird-mammal host switch. Our study reveals previously undiscovered and multi-faceted insights into prehistoric hepatitis B virus evolution and provides valuable resources for future studies, such as in-vitro resurrection of Mesozoic hepadnaviruses.
古病毒学涉及真核生物基因组中内源性病毒元件的鉴定。然而，由于宿主基因组中存在的内源性序列数量较少，乙型肝炎病毒的逆转录进化起源仍然难以捉摸。在这里，我们报告了一个跨越 8200 万至 1210 万年前鸟类进化的乙型肝炎病毒内源性的全面定时代码记录。最古老的病毒遗物跨越了 99%完整的乙型肝炎病毒基因组序列，构成了中生代古病毒基因组的首次发现。我们表明，Hepadnaviridae 比以前已知的要早 6300 多万年，并提供了乙型肝炎病毒和鸟类在中生代和新生代共存的直接证据。最后，系统发育分析和乙型肝炎病毒遗物的分布表明，鸟类可能是 Hepadnaviridae 的原始宿主，而哺乳动物乙型肝炎病毒可能是在鸟类-哺乳动物宿主转换之后出现的。我们的研究揭示了史前乙型肝炎病毒进化的先前未被发现的多方面见解，并为未来的研究提供了有价值的资源，例如中生代 hepadnaviruses 的体外复活。
