Asgard archaea are globally distributed prokaryotic microorganisms related to eukaryotes; however, viruses that infect these organisms have not been described. Here, using metagenome sequences recovered from deep-sea hydrothermal sediments, we characterize six relatively large (up to 117 kb) double-stranded DNA (dsDNA) viral genomes that infected two Asgard archaeal phyla, Lokiarchaeota and Helarchaeota. These viruses encode Caudovirales-like structural proteins, as well as proteins distinct from those described in known archaeal viruses. Their genomes contain around 1–5% of genes associated with eukaryotic nucleocytoplasmic large DNA viruses (NCLDVs) and appear to be capable of semi-autonomous genome replication, repair, epigenetic modifications and transcriptional regulation. Moreover, Helarchaeota viruses may hijack host ubiquitin systems similar to eukaryotic viruses. Genomic analysis of these Asgard viruses reveals that they contain features of both prokaryotic and eukaryotic viruses, and provides insights into their potential infection and host interaction mechanisms.

Asgard古菌是全球分布的与真核生物相关的原核微生物；然而，尚未描述感染这些生物的病毒。在这里，使用从深海热液沉积物中恢复的宏基因组序列，我们描述了感染两个 Asgard 古菌门 Lokiarchaeota 和 Helarchaeota 的六个相对较大（高达 117 kb）的双链 DNA (dsDNA) 病毒基因组。这些病毒编码Caudovirales类结构蛋白，以及与已知古细菌病毒中描述的蛋白质不同的蛋白质。它们的基因组包含大约 1-5% 的与真核细胞核质大 DNA 病毒 (NCLDV) 相关的基因，并且似乎能够进行半自主的基因组复制、修复、表观遗传修饰和转录调控。此外，Helarchaeota 病毒可能劫持宿主泛素系统，类似于真核病毒。对这些 Asgard 病毒的基因组分析表明，它们同时具有原核和真核病毒的特征，并提供了对其潜在感染和宿主相互作用机制的见解。