Egoviruses: distant relatives of poxviruses abundant in the gut microbiome of humans and animals worldwide

Large and giant double-stranded DNA viruses within the phylum Nucleocytoviricota are diverse and prevalent in the environment where they substantially affect the ecology and evolution of eukaryotes. Until now, these viruses were only sporadically found in the digestive system of vertebrates. Here, we present the identification and genomic characterization of a proposed third order of viruses within the class Pokkesviricetes that currently consists of poxviruse s and asfuviruses. Members of this newly identified order we provisionally named “ Egovirales ” are abundant in the digestive system of vertebrates worldwide and occur in high abundances in >10% of livestock animals, >2% of humans, and wild animals. Egoviruses have linear genomes up to 360 kbp in length that likely produce multilayered icosahedral capsids, similar to those of asfuviruses. The diversity of egoviruses already far exceeds that of all known poxviruses and animal-associated asfuviruses. Phylogenetic analyses and patterns of virus distribution across vertebrates suggest that egoviruses can be either specialists or generalists associated with a single or multiple vertebrate species, respectively. Notably, one egovirus clade is human-specific, evolutionarily constrained, and spread across continents, demonstrating a long-lasting association between Egovirales and the human population on the global scale. Egoviruses not only expand the ecological and evolutionary scope of Pokkesviricetes , but also appear to be the most diverse, widespread, and abundant group of double-stranded DNA viruses infecting eukaryotic cells in the digestive system of vertebrates.