Picobirnaviruses turn up in human stool all the time. For 40 years nobody knew what they infect. A Washington University team led by David Wang now has an answer. The viruses grow inside gut bacteria, not inside our cells, which settles a long argument. The researchers watched the virus multiply over 20 days in an oxygen-free culture where human cells cannot live. Antibiotics that killed the bacteria stopped the virus cold. They traced it to a newly named gut bacterium, Candidatus Anaerotignum faecalis. That makes picobirnaviruses only the third known family of RNA viruses that infect bacteria. Human gut cells can still soak up the viral particles and react, but the virus does not replicate in them. High virus levels in sick patients may be a marker of gut trouble rather than a cause. I like this one because it shows how much of our own gut is still a blank map.
Source: Nature Microbiology, 29 October 2026
