Mavericks are virus-like mobile genetic elements found in the genomes of eukaryotes. Although Mavericks encode capsid morphogenesis homologues, their viral particles have not been observed. Here, we provide new evidence supporting the viral nature of Mavericks and the potential existence of virions. To this end, we conducted a phylogenomic analysis of Mavericks in hundreds of vertebrate genomes, discovering 134 elements with an intact coding capacity in 17 host species. We reveal an extensive genomic fossil record in 143 species and date 3 groups of elements to the Late Cretaceous. Bayesian phylogenetic analysis using genomic fossil orthologues suggests that Mavericks have infected osteichthyans for ∼419 million years. They have undergone frequent cross-species transmissions in cyprinid fish and all core genes are subject to strong purifying selection. We conclude that vertebrate Mavericks form an ancient lineage of aquatic dsDNA viruses which are probably still functional in some vertebrate lineages.

中文翻译：

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脊椎动物特立独行病毒样移动遗传元件的系统基因组学

Mavericks是在真核生物基因组中发现的类似病毒的可移动遗传元件。尽管Mavericks编码衣壳形态发生同源物，但尚未观察到它们的病毒颗粒。在这里，我们提供了支持小牛病毒性质和病毒体潜在存在的新证据。为此，我们对Mavericks的数百个脊椎动物基因组进行了系统发育分析，在 17 个宿主物种中发现了 134 个具有完整编码能力的元件。我们揭示了 143 个物种的广泛基因组化石记录，并将 3 组元素追溯到白垩纪晚期。使用基因组化石直系同源物的贝叶斯系统发育分析表明，小牛感染骨鱼已有约 4.19 亿年的历史。它们在鲤鱼中经历了频繁的跨物种传播，所有核心基因都受到强烈的纯化选择。我们得出的结论是，脊椎动物Mavericks形成了一个古老的水生 dsDNA 病毒谱系，这些病毒可能仍然在某些脊椎动物谱系中发挥作用。