A virus that can cause obesity in animals may be linked to some cases of obesity in humans, researchers at the University of Wisconsin Medical School have found.
A preliminary study of 199 people has shown that as many as 15 percent of obese people may carry antibodies to the virus, indirect evidence that they once were exposed to the virus itself. None of the lean volunteers tested had the antibodies.
Dr. Nikhil Dhurandhar described the findings Mon., April 7, at the Experimental Biology annual meeting in New Orleans. An assistant research scientist in the UW Medical School department of medicine, Dhurandhar conducted the research with UW Medical School Professor of Medicine and Nutritional Sciences Dr. Richard Atkinson.
Between 80 and 90 million Americans are obese, defined as having a body-mass index of 27 or above. Body mass index is calculated by dividing a person's weight in kilograms by the square of height in meters. A viral connection to obesity in humans has never been seriously considered before, the researchers noted.
Dhurandhar first found that one type of adenovirus that infects birds and is found only in his native India could induce obesity when it was injected into chickens.
Human adenoviruses form a large family of some 50 viruses. Transmitted through the air, they can cause upper respiratory infections, cold symptoms, gastrointestinal problems and eye inflammation in humans.
Dhurandhar and Atkinson next injected laboratory animals with a form of adenovirus known to affect humans, Ad-36, which resulted in obesity.
"A paradoxical characteristic of the virus is that in animals it appears to produce low levels of cholesterol and triglycerides along with the obesity," said Dhurandhar, noting that obesity is usually accompanied by elevated levels of these substances.