Background Endogenous Retroviruses (ERVs) constitute approximately 8% of every human genome and are relics of ancestral infections that affected the germ line cells. The ERV-W group contributed to primate physiology by providing an envelope protein (Syncytin-1) that has been adopted for placenta development in hominoids. Expression of Human ERV-W (HERV-W) sequences is investigated for a pathological role in various human diseases. Results We previously characterized ERV-W group genomic sequences in human and non-human Catarrhini species. We now investigated ERV-W-like sequences in the parvorder Platyrrhini, especially regarding two species with complete genome assemblies, namely marmoset (Callithrix jacchus) and squirrel monkey (Saimiri boliviensis). We identified in both species proviral sequences, annotated as ERV1-1 in respective genome assemblies, sharing high sequence similarities with Catarrhini ERV-W. A total of 130 relatively intact proviruses from the genomes of marmoset and squirrel monkey were characterized regarding their structural and evolutionarily relationships with Catarrhini ERV-W elements. Platyrrhini ERV-W sequences share several structural features with Catarrhini ERV-W elements and are closely related phylogenetically with the latter as well as with other ERV-W-related gammaretrovirus-like ERVs. The ERV-W group colonized Platyrrhini primates of both Callitrichidae and Atelidae lineages, with provirus formations having occurred mostly between 25 and 15 mya. Two LTR subgroups were associated with monophyletic proviral bodies. A pre-gag region appears to be a sequence feature common to the ERV-W group: it harbors a putative intron sequence that is missing in some ERV-W loci, holding a putative ORF as well. The presence of a long pre-gag portion was confirmed among all gammaretroviral ERV analyzed, suggesting a role in the latter biology. It is noteworthy that, contrary to Catarrhini ERV-W, there was no evidence of L1-mediated mobilization for Platyrrhini ERV-W sequences. Conclusions Our data establish that ERV-W is not exclusive to Catarrhini primates but colonized both parvorders of Simiiformes, providing further insight into the evolution of ERV-W and the colonization of primate genomes.

中文翻译：

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Platyrrhini 物种中 ERV-W 样序列的鉴定和表征为灵长类动物 ERV-W 的进化史提供了新的见解。

背景 内源性逆转录病毒 (ERV) 约占每个人类基因组的 8%，是影响生殖系细胞的祖先感染的遗物。ERV-W 小组通过提供一种已被用于类人猿胎盘发育的包膜蛋白 (Syncytin-1) 为灵长类动物的生理学做出了贡献。研究了人类 ERV-W (HERV-W) 序列的表达在各种人类疾病中的病理作用。结果我们之前在人类和非人类卡他鼻物种中表征了 ERV-W 组基因组序列。我们现在研究了 parvorder Platyrrhini 中的 ERV-W 样序列，特别是关于具有完整基因组组装的两个物种，即狨猴 (Callithrix jacchus) 和松鼠猴 (Saimiri boliviensis)。我们在这两个物种的前病毒序列中都发现了，在各自的基因组组装中注释为 ERV1-1，与 Catarrhini ERV-W 具有高度的序列相似性。来自狨猴和松鼠猴基因组的总共 130 个相对完整的原病毒被表征为它们与卡他鼻 ERV-W 元件的结构和进化关系。Platyrrhini ERV-W 序列与 Catarrhini ERV-W 元件共享几个结构特征，并且在系统发育上与后者以及其他 ERV-W 相关的伽马逆转录病毒样 ERV 密切相关。ERV-W 组定殖了 Callitrichidae 和 Atelidae 谱系的 Platyrrhini 灵长类动物，原病毒形成主要发生在 25 到 15 岁之间。两个 LTR 亚组与单系前病毒体有关。pre-gag 区域似乎是 ERV-W 组共有的序列特征：它包含一个假定的内含子序列，该序列在某些 ERV-W 基因座中缺失，也具有假定的 ORF。在所有分析的 gammaretroviral ERV 中都证实了一个长的 pre-gag 部分的存在，这表明在后一种生物学中的作用。值得注意的是，与Catarrhini ERV-W相反，没有证据表明L1介导的Platyrrhini ERV-W序列动员。结论 我们的数据表明，ERV-W 不是卡他鼻灵长类动物独有的，而是定殖于 Simiiformes 的两种小目动物，为 ERV-W 的进化和灵长类动物基因组的定殖提供了进一步的见解。与Catarrhini ERV-W相反，没有证据表明L1介导的Platyrrhini ERV-W序列动员。结论 我们的数据表明，ERV-W 不是卡他鼻灵长类动物独有的，而是定殖于 Simiiformes 的两种小目动物，为 ERV-W 的进化和灵长类动物基因组的定殖提供了进一步的见解。与Catarrhini ERV-W相反，没有证据表明L1介导的Platyrrhini ERV-W序列动员。结论 我们的数据表明，ERV-W 不是卡他鼻灵长类动物独有的，而是定殖于 Simiiformes 的两种小目动物，为 ERV-W 的进化和灵长类动物基因组的定殖提供了进一步的见解。