A virus that has been linked to obesity in animals and humans works by converting adult stem cells into fat cells, making it easier to gain weight and harder to lose it, researchers reported this week.
At least 10 viruses and bacteria have now been shown to increase obesity rates, and the new study, presented Monday at a Boston meeting of the American Chemical Society, provides the first insight into how the viruses operate.
Adenovirus-36, or Ad-36, is known to cause respiratory and eye infections. Various animal species have been shown to gain excess weight after infection.
Thirty percent of obese Americans, compared with 11% of their thinner counterparts, have antibodies indicating infection, studies suggest.
But how the virus might produce obesity has remained a mystery because researchers cannot ethically infect humans.
As an alternative, Drs. Magdalena Pasarica and Nikhil Dhurandhar of Louisiana State University used the virus to infect fat tissue taken from people undergoing liposuction. Pasarica reported that more than half the stem cells in the tissue were converted to fat cells and began growing as they accumulated and stored fat.
Once fat cells are formed in the body, she noted, they never go away. They can be shrunk, but they remain, waiting for a fresh infusion of fat so they can begin growing again.
If the results can be confirmed, Dhurandhar said, a vaccine against the virus could help reduce obesity rates in future generations.