Global atlas catalogs nearly 55,000 RNA viruses in and around cities

Scientists have created a global catalog of 54,945 RNA viruses found in urban and peri-urban environments, about 77% of which had not previously been documented. The UPVAtlas offers an unusually broad baseline for studying the largely unexplored viral communities that surround people without implying that these viruses are new health threats.

The international study, published in Nature Communications, examined 2,922 samples from 102 cities across 31 countries. Researchers analyzed genetic material from frequently touched surfaces such as handrails, benches and ticket machines, alongside samples from sewage, soil, sediment, freshwater and greenhouses. Metatranscriptomic sequencing and bioinformatics tools allowed the team to sort millions of RNA fragments and identify viral sequences without searching only for known disease-causing organisms.

A possible host could be proposed for only about one-third of the sequences. More than half of that subset were viruses that infect bacteria, underscoring how little of the catalog can currently be connected to human infection. The researchers also identified 166 bacteriophages with histories of infecting clinically important bacteria, providing candidates for future studies of phage therapy and antibiotic resistance.

Sewage contained some of the greatest viral diversity, strengthening its potential value for environmental surveillance. Because discoveries had not begun to level off as more samples were analyzed, the atlas likely captures only a fraction of the diversity present. Future sampling can now reveal how urban viral communities change over time.