Global Distribution, Genomic Diversity, and Phylogeny of Aoguangviridae

Marine Group II (MGII) archaea are abundant and constitute an ecologically essential portion of marine microbial communities in the upper layers of the ocean, where they make a substantial contribution to organic matter degradation and carbon cycling. Aoguangviridae , which is one of the earliest recognized viral groups linked to MGII archaea, has been detected in a range of marine environments, but its diversity, evolution, and ecological distribution remain unclear. In this work, the diversity and ecology of Aoguangviridae across the global oceans are systematically characterized by integrating global virome resources with metagenomic and metatranscriptomic datasets. Furthermore, a nonredundant genomic dataset compiled from datasets with 59 to 227 genomes, including 168 newly identified uncultivated viral genomes, was expanded. The viruses in this dataset were resolved into 22 subfamilies and 157 genera that displayed conserved modular genome organization. Comparative genomic and phylogenetic analyses identified 7 types of putative auxiliary viral genes and suggested a phylogenetic affinity between representative viral genes and MGII archaeal homologs, which is consistent with a possible host–virus gene exchange. Aoguangviridae are widely distributed across marine and coastal habitats worldwide, with the highest abundance in epipelagic and polar environments. Transcriptional activity was found to vary markedly among lineages and to generally be the highest in the deep chlorophyll maximum layer. Taken together, these findings expand our understanding of the diversity, evolution, biogeography, and transcriptional activity of Aoguangviridae across global oceans.