Too fat? Common virus may be to blame: study

By Julie Steenhuysen

CHICAGO (Reuters) - A common virus caused human adult stem cells to turn into fat cells and could explain why some people become obese, U.S. researchers said on Monday.

The research builds on prior studies of adenovirus-36 -- a common cause of respiratory and eye infections -- and it may lead to an obesity vaccine, they said.

"We're not talking about preventing all types of obesity, but if it is caused by this virus in humans, we want a vaccine to prevent this," said Nikhil Dhurandhar, an associate professor at Pennington Biomedical Research Center at Louisiana State University System.

The virus adenovirus-36 or Ad-36, caused animals to pack on the pounds in lab experiments. "These animals accumulated a lot of fat," Dhurandhar said in a telephone interview.

Dhurandhar also has shown that obese people were three times more likely to have been infected with Ad-36 than thin people in a large study of humans.

Now, researchers in Dhurandhar's lab have shown that exposure to the virus caused adult human stem cells to turn into fat-storing cells.

Dr. Magdalena Pasarica, who led the study, obtained adult stem cells from fat tissue of people who had undergone liposuction. Stem cells are a type of master cell that exist in an immature form and give rise to more specialized cells.

Half of the stem cells were exposed to the virus Ad-36. After a week, most of the infected stem cells developed into fat cells, while the uninfected cells were unchanged.