It may be hiding cosily in your gut. Or perhaps your partner's or your neighbours. In fact, it's been hidden inside millions of people for years and never been noticed before. But now researchers think it’s the most common and abundant virus in the human stomach.
The ‘cheeky’ virus, dubbed crAssphage, is quite a master of disguise. Researchers hadn’t spotted it before because it lives inside gut microbes known as bacteroides—gram-negative bacteria that may play an important role in the development of obesity and diabetes. These type of bacteria include most of the ones usually found in the human gastrointestinal tract, but they are also responsible for certain diseases, such as bacterial meningitis.
And just like many other discoveries scientific, this one happened by accident.
The virus was discovered by scientists at the San Diego State University in the US, who were analysing faecal samples from people in America, Korea, Japan and Europe.
According to Michaeleen Doucleff at NPR, the researchers noticed that a “few genes from the same virus kept of popping up over and over again. So they painstakingly stitched together the virus’s genome inside the computer."
And they found the virus in 75 percent of the 466 samples analysed—and they couldn’t find information about it in the scientific literature.
“It’s not unusual to go looking for a novel virus and find one,” team member, bioinformatics professor Robert A. Edwards, said in a press release. “But it’s very unusual to find one that so many people have in common. The fact that it’s flown under the radar for so long is very strange.” Edwards believes the virus may be as old as humans are.
The researchers still need to figure out what role the newly found virus has in our gut. Because it’s attached to bacteriodetes, it could also play a role in obesity and gut-related diseases, but we won't know for sure until further studies are conducted.
The results of the study were published in the journal Nature Communications.