According to a study in Nature Communications, scientists have discovered a previously unknown virus living in the human gut.
Exploring genetic material found in intestinal samples, the international team uncovered the crAssphage virus.
They say the virus could influence the behavior of some of the most common bacteria in our gut.
Experts say these types of viruses, called bacteriophages, have been shown to play a role in chronic diseases.
Led by a team at San Diego State University, scientists scoured genetic information stored in three large international databases.
They stumbled upon a piece of DNA, some 100,000 letters long, present in more than half of all samples from the gut.
And while cross-checking its identity in global directories they realized it had never been described before.
Prof. Robert Edwards, lead author, said: “It is not unusual to go looking for a novel virus and find one.
“But it’s very unusual to find one that so many people have in common.
“The fact it has flown under the radar for so long is very strange.”
Researchers say the virus has the genetic fingerprint of a bacteriophage – a type of virus known to infect bacteria.
Phages may work to control the behavior of bacteria they infect – some make it easier for bacteria to inhabit in their environments while others allow bacteria to become more potent.
Prof. Robert Edwards said: “In some way phages are like wolves in the wild, surrounded by hares and deer.
“They are critical components of our gut ecosystems, helping control the growth of bacterial populations and allowing a diversity of species.”
According to the team, crAssphage infects one of the most common types of bacteria in our guts.
They are now trying to grow the virus in a laboratory. And they say the next step would be to work out exactly how the virus affects our gut bacteria.