Picobirnaviruses infect gut bacteria, not human cells — News-Medical

Researchers at Washington University School of Medicine in St. Louis have found that picobirnaviruses, which for years were considered possible causes of intestinal diseases in humans, actually infect bacteria in the gut. The results of the study, published on October 29 in the journal Nature Microbiology, were reported by News-Medical.

The virus replicated among bacteria

Picobirnaviruses were first detected in stool samples from patients with diarrhea nearly four decades ago. At the time, they were found alongside rotaviruses and noroviruses, so scientists assumed that these viruses directly infect human cells and may cause gastrointestinal disorders.

The authors of the new study tested a different hypothesis: that picobirnaviruses infect bacteria. They introduced human stool samples into germ-free mice, creating a laboratory model in which the virus could actively replicate. The viral population from the mice's intestines was then cultured in laboratory dishes with gut bacteria under oxygen-free conditions.

More current news is available on the UA.News Telegram channel Telegram.

According to the researchers, the virus replicated for 20 days. Since mammalian cells cannot survive without oxygen, this indicated that the virus was replicating in bacteria. Antibiotics that destroyed bacteria also stopped the virus from replicating.

A bacterial host was identified

Using molecular imaging and cell sorting, the scientists identified picobirnaviruses in a previously unidentified gut bacterium, named Candidatus Anaerotignum faecalis. The study classifies the Picobirnaviridae family as the third known family of RNA bacteriophages — viruses that infect bacteria.

The presence of picobirnaviruses in the gut had previously been linked to acute diarrhea, graft-versus-host disease after stem cell transplantation, and type 1 diabetes. At the same time, high levels of the virus in patients with these conditions do not prove that it causes the disease. According to the researchers, picobirnavirus may destroy beneficial gut bacteria, affecting the microbiome, or serve as a biomarker of intestinal disorders.