Eukaryotic viruses and bacteriophage have been implicated in disease and bleaching in corals, but the compositional and functional diversity of these viruses in healthy and compromised hosts remains underexplored. To investigate whether viral assemblages differ in concert with coral bleaching, we collected bleached and non-bleached conspecific pairs of corals during a minor bleaching event in 2016 from reefs on the island of Mo’orea, French Polynesia. Using electron microscopy (EM), we identified several viral particle types, all reminiscent of medium to large-sized nucleocytoplasmic large DNA viruses (NCLDV). We also found that viral metagenomes from bleached corals have significantly more eukaryotic virus sequences, whereas bacteriophage sequences are significantly more abundant in viral metagenomes from non-bleached colonies. In this study, we also initiated the assembly of the first eukaryotic dsDNA coral virus genome. Based on our EM imagery and our taxonomic annotations of viral metagenome sequences, we hypothesize that this genome represents a novel, phylogenetically distinct member of the NCLDVs, with its closest sequenced relative being a distant marine flagellate-associated virus. We also showed that this NCLDV is abundant in bleached corals, but it is also present in apparently healthy corals, suggesting it plays a role in the onset and/or severity of coral bleaching.

中文翻译：

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与核质大 DNA 病毒差异丰度相关的珊瑚漂白表型

真核病毒和噬菌体与珊瑚的疾病和白化有关，但这些病毒在健康和受损宿主中的组成和功能多样性仍未得到充分探索。为了研究病毒组合是否与珊瑚白化一致，我们在 2016 年法属波利尼西亚莫雷阿岛的珊瑚礁的一次小型白化事件中收集了白化和未白化的同种珊瑚对。使用电子显微镜 (EM)，我们确定了几种病毒颗粒类型，都让人联想到中型到大型核质大 DNA 病毒 (NCLDV)。我们还发现，来自漂白珊瑚的病毒宏基因组具有明显更多的真核病毒序列，而来自非漂白菌落的病毒宏基因组中的噬菌体序列明显更多。在这项研究中，我们还启动了第一个真核 dsDNA 珊瑚病毒基因组的组装。基于我们的 EM 图像和我们对病毒宏基因组序列的分类学注释，我们假设该基因组代表 NCLDV 的一个新的、系统发育不同的成员，其最接近的测序亲属是远距离海洋鞭毛虫相关病毒。我们还表明，这种 NCLDV 在白化珊瑚中含量丰富，但它也存在于明显健康的珊瑚中，表明它在珊瑚白化的发生和/或严重程度中起作用。其最接近的测序亲属是一种遥远的海洋鞭毛虫相关病毒。我们还表明，这种 NCLDV 在白化珊瑚中含量丰富，但它也存在于明显健康的珊瑚中，表明它在珊瑚白化的发生和/或严重程度中起作用。其最接近的测序亲属是一种遥远的海洋鞭毛虫相关病毒。我们还表明，这种 NCLDV 在白化珊瑚中含量丰富，但它也存在于明显健康的珊瑚中，表明它在珊瑚白化的发生和/或严重程度中起作用。