Abstract：
Compared to free-living viruses (< 0.22 m) in the ocean, planktonic viruses in the \"cellular fraction\" (0.22 ~ 3.0 μm) are now far less well understood, and the differences between them remain largely unexplored. Here, we revealed that even in the same seawater samples, the \"cellular fraction\" comprised significantly distinct virus communities from the free virioplankton, with only 13.87% overlap in viral contigs at the species level. Compared to the viral genomes deposited in NCBI RefSeq database, 99% of the assembled viral genomes in the \"cellular fraction\" represented novel genera. Notably, the assembled (near-) complete viral genomes within the \"cellular fraction\" were significantly larger than that in the \"viral fraction,\" and the \"cellular fraction\" contained three times more species of giant viruses or jumbo phages with genomes > 200 kb than the \"viral fraction.\" The longest complete genomes of jumbo phage (~ 252 kb) and giant virus (~ 716 kb) were both detected only in the \"cellular fraction.\" Moreover, a relatively higher proportion of proviruses were predicted within the \"cellular fraction\" than \"viral fraction.\" Besides the substantial divergence in viral community structure, the different fractions also contained their unique viral auxiliary metabolic genes; e.g., those potentially participating in inorganic carbon fixation in deep sea were detected only in the \"cellular-fraction\" viromes. In addition, there was a considerable divergence in the community structure of both \"cellular fraction\" and \"viral fraction\" viromes between the surface and deep-sea habitats, suggesting that they might have similar environmental adaptation properties. The findings deepen our understanding of the complexity of viral community structure and function in the ocean.
摘要：
与海洋中的自由生活病毒（<0.22m）相比，“细胞部分”(0.22~3.0μm)中的浮游病毒现在知之甚少，它们之间的差异在很大程度上仍未被探索。这里,我们发现即使在相同的海水样本中，“细胞部分”包括与自由浮游病毒明显不同的病毒群落，在物种水平上，病毒重叠群只有13.87％的重叠。与NCBIRefSeq数据库中保存的病毒基因组相比，“细胞部分”中99％的组装病毒基因组代表了新属。值得注意的是,“细胞部分”中组装的（近）完整的病毒基因组明显大于“病毒部分”中的病毒基因组，\"和\"细胞部分\"包含的基因组>200kb的巨型病毒或巨型噬菌体的物种比\"病毒部分多三倍。仅在细胞部分中检测到大型噬菌体（〜252kb）和巨型病毒（〜716kb）的最长完整基因组。\"此外，预计“细胞部分”中的前病毒比例高于“病毒部分”。“除了病毒群落结构的巨大分歧，不同的部分还含有其独特的病毒辅助代谢基因；例如，那些可能参与深海无机碳固定的病毒仅在“细胞部分”病毒中检测到。此外,表面和深海栖息地之间的“细胞部分”和“病毒部分”病毒的群落结构存在相当大的差异，表明它们可能具有相似的环境适应性。这些发现加深了我们对海洋中病毒群落结构和功能复杂性的理解。
