July 28, 2014

Newly Discovered Gut Virus Could Play A Role In Obesity, Diabetes

redOrbit Staff & Wire Reports - Your Universe Online

A previously undetected virus, discovered in intestinal samples, could influence the behavior of common gut bacteria and could even play a role in conditions such as diabetes and obesity, according to a new Nature Communications study.

According to BBC News health reporter Smitha Mundasad, scientists from San Diego State University were exploring genetic material found in intestinal samples when they discovered a new type of bacteriophage which they have dubbed the crAssphage virus.

The virus, the study authors explained, is present in more than half of the world’s population – and it was apparently discovered by accident. CrAssphage, as it turns out, was first detected when SDSU bioinformatics professor Robert A. Edwards discovered an unusual cluster of viral DNA while studying the samples of 12 individuals.

The viral DNA strand was approximately 97,000 base pairs long, and was common to each of the samples. Edwards and his associates checked their discovery against a comprehensive listing of known viruses, but found no match. They then screened for it across the National Institute of Health’s Human Microbiome Project (HMP) and Argonne National Laboratory's MG-RAST databases, and again found it in several human fecal samples.

In order to prove the viral DNA they found in the computer data was actually present in nature, SDSU virologist John Mokili used a technique known as DNA amplification, which helped them locate the virus in the samples originally used to construct the NIH database. Mokili was able to find “biological proof” of its existence.

“It’s 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 that it’s flown under the radar for so long is very strange,” Edwards, who was the paper’s lead author, said in a statement Thursday. “We’ve basically found it in every population we’ve looked at. As far as we can tell, it’s as old as humans are.”

CrAssphage is what is known as a bacteriophage, meaning it is a virus which is known to infect and replicate inside bacteria. Mundasad said that the SDSU team is now attempting to grow the virus in the laboratory, and if that proves successful, they will attempt to figure out exactly how this pathogen affects our gut bacteria.

That has proven somewhat challenging as the researchers have had difficulty gathering details about crAssphage. For instance, they currently do not know how it is transmitted, but the fact that it was not present in the fecal samples of young infants suggests that it is not passed from mother to child – it is acquired later in childhood.

The viral DNA’s makeup suggests that it has a circular structure, and it has been confirmed that it is a singular entity. However, it has been difficult for the team to isolate it. Once they do capture it, they want to see what impact it has on weight gain – does it promote or suppress obesity-related processes in a person’s gut?

Likewise, the study authors suggest that the virus could be used to mitigate or prevent other diseases affected by the gut, including diabetes and other gastroenterological ailments. Once they better understand the processes, Edwards believes that this could lead to personalized medicine based on the crAssphage – “we could isolate your particular strain of the virus, manipulate it to target harmful bacteria, then give it back to you,” he explained.

In addition, Dr. Martha Clokie of the University of Leicester, who was not involved in the study, told BBC News it was “exciting” that the SDSU team were able to produce “new techniques and powerful tools to help identify previously unknown viruses. And thinking longer term, we know bacteria can play an important role in chronic diseases such as obesity and diabetes. If we can pin down these viral controllers, we could perhaps one day use them to modify any harmful bacteria, rendering them less powerful.”

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