Virus Could Help Drive Obesity

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Funded by the NIH, Pasarica's current effort focused on the impact of Ad-36 viral infection on fatty tissue extracted from adult male and female liposuction patients.

Stem cells can develop into a variety of cell types. In this study, the researchers obtained adult stem cells from the tissue samples and then infected half of the cells with the virus. The cells were allowed to grow in culture for about a week.

By the end of that period, most of the infected cells infected with Ad-36 had developed into so-called "pre-fat" cells, but the uninfected cells did not.

The more virus they inserted into the cells, the greater the fat growth observed, the researchers said. This effect was evident among tissue taken from both men and women.

In addition, the virally-exposed pre-fat cells were found to collect fat at a faster than normal rate, resulting in a double-whammy effect -- more, and bigger fat cells.

The team was also able to identify a particular gene in the Ad-36 virus -- known as E4Orfl -- that appears to be directly responsible for the promotion of fat growth. The identification of this gene provides a target for future anti-obesity therapies, the team said.

Exactly how the virus might cause obesity remains unclear. The researchers are also unsure of the length of time the virus might remain in infected patients and how long its effects continue even if it is eradicated.

Pasarica said much more research is needed to explore all these questions.

Dr. Barbara B. Kahn, chief of the division of endocrinology, diabetes, and metabolism at Beth Israel Deaconess Medical Center in Boston, said the findings were still "inconclusive" and not a license to overeat.

"The bottom-line on the viral thing is it's very intriguing, (and) it definitely deserves more investigation, but while it may be a contributing factor, it's certainly not going to explain the majority of obesity in our society," said Kahn, who is also a professor of medicine at Harvard Medical School.

"In general, to become obese there has to be some sort of mismatch between energy intake and energy expenditure," she noted. Again, that gets back to the same old advice: Eat healthfully and exercise regularly to keep weight under control.

More information

There's more on the causes of obesity at ObesityinAmerica.