A common virus that causes throat and eye infections may also play a role in obesity,
according to US scientists. Laboratory tests found the virus triggered changes
in human fat tissue that left people with more, and larger, fat cells than people
who were not infected.
The scientists acknowledge the virus may be only a contributing factor to growing
obesity rates, but they believe that understanding how fat cells respond to
infection could lead to vaccines to prevent weight gain and possibly to fat-promoting
treatments for people with rare wasting conditions, such as lipidystrophy.
The infection is three times more common in obese people and may explain the
"healthy obese", who are substantially overweight but have healthy
blood pressure and cholesterol levels. The study builds on work that linked
the virus to animal obesity but is the first to suggest infection may drive
weight gain in humans.
Magdelena Pasarica and Nikhil Dhurandhar at Pennington biomedical centre, Louisiana
State University, collected fatty tissue from 10 patients having liposuction.
They extracted stem cells from the tissue and exposed half from each patient
to adenovirus-36, a cause of respiratory tract infections, diarrhoea and conjunctivitis.
A week later, many stem cells exposed to the virus had been converted into
early stage fat cells and begun storing fat. In samples that were not infected,
a third as many stem cells had become fat cells.
"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,"
Dr Pasarica told the annual meeting of the American Chemical Society in Boston.