A group of segmented viruses contains genome segments sharing homology with multiple viral taxa.

The discovery of diverse segmented RNA viruses through metatranscriptomics has enabled researchers to trace their evolutionary trajectories. However, this effort has been hindered by the limited availability of complete genome sequences and the low similarity of novel viral segments. In this study, we characterized Fusarium asiaticum vivivirus 1 (FaVvV1), a +ssRNA mycovirus with 10 monocistronic RNA segments (S1 to S10, encoding VP1 to VP10), present in the phytopathogenic fungus IMPORTANCE: Metaviromics has greatly expanded our understanding of viral diversity, including segmented or multipartite RNA viruses with genomes composed of multiple segments. However, virome analyses often fail to detect genomic segments beyond the RdRP, likely due to their low similarity to known viruses. We characterized a group of segmented, potentially multipartite, +ssRNA viruses, with Fusarium asiaticum vivivirus 1 as a representative; most of these viruses likely infect fungi. Through structural and evolutionary analysis of the five core segments of viviviruses, our findings highlight key aspects of vivivirus evolution, including genome segmentation, gene and domain duplications, and segments with multiple evolutionary origins.