Researchers presented further evidence today that obesity in some cases might be contagious.
A common virus, implicated in previous studies as a possible cause of obesity, was found in lab tests to transform adult stem cells obtained from fat tissue into fat cells. A gene in the virus has now been found to be the likely culprit.
“We’re not saying that a virus is the only cause of obesity, but this study provides stronger evidence that some obesity cases may involve viral infections,” said Dr. Magdalena Pasarica of Louisiana State University.
“Not all infected people will develop obesity,” Pasarica said. “We would ultimately like to identify the underlying factors that predispose some obese people to develop this virus and eventually find a way to treat it.”
The virus is a human adenovirus-36 (Ad-36), known to cause respiratory and eye infections. Previous research has shown that it causes fat to accumulate in animals, and other work found that 30 percent of obese people were infected with the Ad-36 virus in comparison to 11 percent of lean people. But no one has shown clearly that the virus actually causes fat levels to increase in human cells.
In the new study, Pasarica and her associates obtained adult stem cells from fatty tissue of patients who had undergone liposuction. Half of the stem cells were exposed to the virus and the other half were not. Most of the virus-infected cells developed into fat cells, while the non-infected cells did not.
The research, funded by the National Institutes of Health (NIH), was presented at a meeting of the American Chemical Society.
About 97 million U.S. adults are overweight or obese, according to the NIH. They face an increased risk of Type 2 diabetes, coronary heart disease, stroke, gallbladder disease, osteoarthritis and other health disorders.
Obesity has many established causes, the researchers point out. Among them: over-eating, eating high-fat foods, lack of exercise, a genetic predisposition and certain medications.
The exact mechanism by which the virus might cause obesity in people is not known, Pasarica said.