Nucleocytoplasmic large DNA and Mirusviricota viruses exhibit taxonomic richness which continually expands due to metagenomic sequencing. Here we curate a database of giant virus metagenome-assembled genomes (GVMAGs V2), comprising 8,508 species-level representatives from 18,727 GVMAGs, a sixfold increase from the previous giant virus phylogenetic frameworks. Phylogenomics revealed 712 previously undescribed genera, 13 previously unknown viral families and an order we propose named Mycodnavirales. By accounting for alternative and custom genetic codes, we improved gene calling in over 1,300 GVMAGs, enabling more accurate identification of protein-coding genes. Database mining uncovered putative endogenous viral elements in hosts spanning algae, fungi and parasitic protists, highlighting that giant virus integration is widespread and evolutionarily persistent. Protein-level analysis revealed enriched genes for pollutant degradation in Algavirales and widespread biosynthetic gene clusters linked to antimicrobial-like and antibiotic resistance gene-like activity. This public resource will serve as a foundation for expanding giant virus diversity, uncovering virus–host interactions and exploring viral evolution. This curated genome-resolved, metagenomic resource expands the known diversity of Nucleocytoviricota and Mirusviricota lineages.
Yumary M. Vasquez, Tiago Nardi, G. M. Terasaki et al.· Nature Microbiology· 1 citation
Giant viruses of the phylum Nucleocytoviricota have emerged as particularly notable due to their increasingly recognized impacts on eukaryotic genome evolution. Their origins are hypothesized to predate or coincide with the diversification of eukaryotes, and they have been detected in hosts that span the eukaryotic tree of life. But surprisingly, such viruses have not been definitively found in Kingdom Fungi, though earlier genomic and metagenomic work suggests putative associations. Here we report both “viral fossils” and active infection by giant viruses in fungi, particularly in the zoosporic phyla Blastocladiomycota and Chytridiomycota. The recovered viral assemblies span up to 350 kb, encode over 300 genes, and form a monophyletic family-level clade within the Nucleocytoviricota related to orders Imitervirales and Algavirales, which we name Mycodnaviridae. We observed variation in infection status among the isolates including apparent active infection and transcriptionally suppressed states, suggesting that viral activation may be constrained to certain life stages of the host. Our experimental findings add to the limited natural virus-host systems available in culture for the study of giant viruses and expand the known host range of Nucleocytoviricota into a new kingdom that contains many model species. Mycodnaviridae have a global distribution, which invites inquiry into the implications of these infections for host traits, host genome evolution, and the metabolic impacts on ecosystems.
J. Myers, Frederik Schulz, Saleh Rahimlou et al.· PLoS Biology· 1 citation
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