Newly Discovered Virus Lives in Half the World’s Population

Jul 27, 2014

By Rachael Rettner


A virus that lives in the human gut has just been discovered, and to the surprise of scientists, it can be found in about half the world’s population, according to a new study.

While it’s not yet clear exactly what the virus does, scientists are eager to find out whether it promotes health or influences susceptibility to certain conditions, said Robert Edwards, a bioinformatics professor at San Diego State University and one of the researchers who worked on the study.

The researchers first uncovered hints of the virus after analyzing DNA from fecal samples of 12 people. They found a cluster of viral DNA that all the samples had in common, Edwards said.

Next, the researchers searched a large database of genetic sequences in samples taken from people living on several different continents, looking for the virus’s DNA sequence, and found the virus in 75 percent of samples of human feces. However, some of these samples were from the same person, Edwards said, so after taking this into account, the researchers estimated that the virus is present in about half of all people.

But how could such a common virus go unnoticed for so long? One of the reasons may be that previously, most researchers compared DNA from current samples only to DNA sequences already known to exist, Edwards said. But in the new study, the researchers first compared the DNA in their samples to one another, looking for common sequences.

“[We] did some different kinds of comparisons, and it jumped right out at us as being something important because it was abundant,” told Edwards Live Science.

The new virus, which the researchers have named crAssphage, is a type of virus known as a bacteriophage, meaning it infects bacteria. It’s likely that crAssphage infects a very common type of gut bacteria called Bacteroidetes, according to the study.

6 comments on “Newly Discovered Virus Lives in Half the World’s Population

  • 2
    God fearing Atheist says:

    If this virus does occur in approximately 50% of the population it is the ideal percentage to determine its effect.
    Statistically the researchers couldn’t get a better number!

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  • There’s that game, Plague, where you can play as a Zombie Virus, and your best chance of winning (meaning, killing the entire earth population) is infecting as many as you can before being detected.

    Zombie Apocalypse confirmed? 🙂

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  • It seems to me we have discovered the ideal parasite. Now, we just have to keep an eye on the little devil that it doesn’t react, say, with plastic microparticles in our gut, and morph into something destructive. Hmm. Might give the rest of the earth a break, though.

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  • Bacterial viruses, called phages (viruses that infect and kill bacteria) have been well studied since 1917. They are routinely used in Former Soviet Union areas to treat antibiotic resistant bacterial infections. Aidan Coffey, [Link to website removed by moderator]

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