Underexplored diversity and transmission of RNA viruses in Antarctic aquatic animals

Antarctic extreme environmental conditions harbor unique ecosystems with underexplored viral diversity. While viruses in Antarctic mammals and birds have been previously documented, the viromes of ecologically pivotal aquatic species, such as Antarctic krill ( Euphausia superba ), remain largely unknown. Here, we characterize RNA viromes from Antarctic species employing metatranscriptomic sequencing of 403 samples collected from the seas near the Antarctic Peninsula and South Shetland Islands, the South Orkney Islands, and South Georgia Island (all in Western Antarctica), and the Cosmonauts Sea (Eastern Antarctica) during 2019–2024. We identified 58 RNA viruses across 19 families/clades, including positive-sense, single-stranded RNA ( n = 37), negative-sense, single-stranded RNA ( n = 5), and double-stranded RNA ( n = 16) viruses. A total of 51 viruses (88%) were novel, revealing extensive hidden viral diversity in Antarctic animals. We performed α- and β-diversity analyses which revealed that host specificity significantly shaped virome composition, while the influence of geographic location warranted further study. Notably, we detected near-identical strains of Lawrence virus (99.35% RdRp identity), Vespucci virus (97.70–99.08%), and a picornavirus in Antarctic krill/fish and their predators, the chinstrap penguin ( Pygoscelis antarcticus ) and the Antarctic fur seal ( Arctocephalus gazella ), suggestive of potential cross-species transmission through food chains. Our findings reveal previously underexplored virome diversity in Antarctic aquatic ecosystems, underscore the evolutionary adaptability of RNA viruses in extreme habitats, and provide essential data for biosecurity assessments concerning the potential movement of viral pathogens in polar and connected ecosystems. Video Abstract