Cold virus may also cause obesity

22 August, 2007:

A common virus that causes cold and eye infections may also lead to obesity.

A research presented at the national meeting of the American Chemical Society on August 20, 2007, says that infection with human adenovirus-36 (Ad-36) seems to direct adult stem cells from fat tissue to turn into fat cells. Stem cells not exposed to the virus, in contrast, were unchanged.

The researchers also identified the specific gene in the virus that appears to be involved in this obesity-promoting effect: E4Orfl.

The field of research investigating the role of viruses in obesity – called infectobesity – is still relatively new and experimental. Researchers, however, do not believe that infection with one of these pathogens is the sole cause of obesity, but they say that some obesity cases may involve viral infections.

Dr Magdalena Pasarica, of the Pennington Biomedical Research Center at Louisiana State University in Baton Rouge, the United States, who presented the study, said researchers do not believe that everyone who has been infected with Ad-36, which is widespread in nature, will develop obesity.

The researchers, she added, 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.

Dr Pasarica was part of a research group that demonstrated that the Ad-36 virus was capable of causing animals infected with the virus to accumulate fat.

The study group, led by Dr Nikhil Dhurandhar, an associate professor at Louisiana State University, also conducted an epidemiologic study that found that 30% of obese people were infected with the Ad-36 virus in comparison to just 11% of lean individuals.

However, evidence that the virus could actually cause fat levels to increase in human cells was lacking until now, Dr Pasarica said.

In the current study, researchers obtained adult stem cells from fatty tissue from a broad cross-section of patients who had undergone liposuction. Half of the stem cells were exposed to Ad-36. After about a week of growth in tissue culture, most of the virus-infected adult stem cells developed into fat cells.

Dr Pasarica and her associates are now in the process of trying to identify the factors that predispose some people with Ad-36 to develop obesity while others do not. She does not rule out the possibility that other human viruses may also contribute to obesity.