Littlejohn Margaret, Locarnini Stephen, Yuen Lilly
Molecular Research and Development, Victorian Infectious Diseases Reference Laboratory, Doherty Institute, Melbourne 3000, Australia.
Cold Spring Harb Perspect Med. 2016 Jan 4;6(1):a021360. doi: 10.1101/cshperspect.a021360.
Members of the family Hepadnaviridae fall into two subgroups: mammalian and avian. The detection of endogenous avian hepadnavirus DNA integrated into the genomes of zebra finches has revealed a deep evolutionary origin of hepadnaviruses that was not previously recognized, dating back at least 40 million and possibly >80 million years ago. The nonprimate mammalian members of the Hepadnaviridae include the woodchuck hepatitis virus (WHV), the ground squirrel hepatitis virus, and arctic squirrel hepatitis virus, as well as a number of members of the recently described bat hepatitis virus. The identification of hepatitis B viruses (HBVs) in higher primates, such as chimpanzee, gorilla, orangutan, and gibbons that cluster with the human HBV, as well as a number of recombinant forms between humans and primates, further implies a more complex origin of this virus. We discuss the current theories of the origin and evolution of HBV and propose a model that includes cross-species transmissions and subsequent recombination events on a genetic backbone of genotype C HBV infection. The hepatitis delta virus (HDV) is a defective RNA virus requiring the presence of the HBV for the completion of its life cycle. The origins of this virus remain unknown, although some recent studies have suggested an ancient African radiation. The age of the association between HDV and HBV is also unknown.
嗜肝DNA病毒科的成员分为两个亚组：哺乳动物亚组和鸟类亚组。整合到斑胸草雀基因组中的内源性禽嗜肝DNA病毒DNA的检测揭示了嗜肝DNA病毒的一个此前未被认识到的深度进化起源，可追溯到至少4000万年前，甚至可能超过8000万年前。嗜肝DNA病毒科的非灵长类哺乳动物成员包括土拨鼠肝炎病毒（WHV）、地松鼠肝炎病毒和北极松鼠肝炎病毒，以及最近描述的蝙蝠肝炎病毒的一些成员。在黑猩猩、大猩猩、猩猩和长臂猿等高等灵长类动物中鉴定出与人类乙肝病毒聚集的乙肝病毒（HBV），以及人与灵长类动物之间的一些重组形式，进一步暗示了这种病毒的起源更为复杂。我们讨论了乙肝病毒起源和进化的当前理论，并提出了一个模型，该模型包括跨物种传播以及随后在C基因型乙肝病毒感染的遗传主干上发生的重组事件。丁型肝炎病毒（HDV）是一种缺陷RNA病毒，其生命周期的完成需要乙肝病毒的存在。这种病毒的起源仍然未知，尽管最近的一些研究表明其起源于古代非洲。HDV与HBV关联的时间也未知。
