Giant viruses are a group of eukaryotic double-stranded DNA viruses with large virion and genome size that challenged the traditional view of virus. Newly isolated strains and sequenced genomes in the last two decades have substantially advanced our knowledge of their host diversity, gene functions, and evolutionary history. Giant viruses are now known to infect hosts from all major supergroups in the eukaryotic tree of life, which predominantly comprises microbial organisms. The seven well-recognized viral clades (taxonomic families) have drastically different host range. Mimiviridae and Phycodnaviridae, both with notable intrafamilial genome variation and high abundance in environmental samples, have members that infect the most diverse eukaryotic lineages. Laboratory experiments and comparative genomics have shed light on the unprecedented functional potential of giant viruses, encoding proteins for genetic information flow, energy metabolism, synthesis of biomolecules, membrane transport, and sensing that allow for sophisticated control of intracellular conditions and cell-environment interactions. Evolutionary genomics can illuminate how current and past hosts shape viral gene repertoires, although it becomes more obscure with divergent sequences and deep phylogenies. Continued works to characterize giant viruses from marine and other environments will further contribute to our understanding of their host range, coding potential, and virus-host coevolution.

中文翻译：

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真核巨型病毒的宿主范围和编码潜力

巨型病毒是一组具有巨大病毒颗粒和基因组大小的真核双链DNA病毒，挑战了传统的病毒观点。过去二十年中新分离的菌株和测序的基因组极大地提高了我们对其宿主多样性、基因功能和进化历史的了解。现在已知巨型病毒可以感染真核生命树中所有主要超类群的宿主，真核生命树主要由微生物组成。七个公认的病毒进化枝（分类科）具有截然不同的宿主范围。拟菌病毒科和藻DNA病毒科都具有显着的科内基因组变异，并且在环境样本中丰度较高，其成员可以感染最多样化的真核生物谱系。实验室实验和比较基因组学揭示了巨型病毒前所未有的功能潜力，它们编码用于遗传信息流、能量代谢、生物分子合成、膜运输和传感的蛋白质，从而可以对细胞内条件和细胞-环境相互作用进行复杂的控制。进化基因组学可以阐明当前和过去的宿主如何塑造病毒基因库，尽管它因不同的序列和深层系统发育而变得更加模糊。持续研究海洋和其他环境中巨型病毒的特征将进一步有助于我们了解其宿主范围、编码潜力和病毒与宿主的共同进化。