[PHNUTR-L] Identifying the human adenoviruses that may make us fat

[Kathrynne Holden, MS, RD]

Colleagues, the following is FYI and does not necessarily reflect my own
opinion. I have no further knowledge of the topic. If you do not wish to
receive these posts, set your email filter to filter out any messages
coming from   @nutritionucanlivewith.com    and the program will remove
anything coming from me.
---------------------------------------------------------
Public release date: 30-Jan-2006
http://www.eurekalert.org/pub_releases/2006-01/aps-coi012506.php

Contact: Christine Guilfoy
cguilfoy at the-aps.org
301-634-7253
American Physiological Society

Contagious obesity? Identifying the human adenoviruses that may make us fat

Human adenoviruses may cause human obesity, but more research is needed 
before a screening test and vaccine become reality. Meanwhile, one 
researcher advises, 'Eat right, exercise, wash your hands'
There is a lot of good advice to help us avoid becoming obese, such as 
"Eat less," and "Exercise." But here's a new and surprising piece of 
advice based on a promising area of obesity research: "Wash your hands."

There is accumulating evidence that certain viruses may cause obesity, 
in essence making obesity contagious, according to Leah D. Whigham, the 
lead researcher in a new study, "Adipogenic potential of multiple human 
adenoviruses in vivo and in vitro in animals," in the January issue of 
the American Journal of Physiology-Regulatory, Integrative and 
Comparative Physiology published by the American Physiological Society.

The study, by Whigham, Barbara A. Israel and Richard L. Atkinson, of the 
University of Wisconsin, Madison, found that the human adenovirus Ad-37 
causes obesity in chickens. This finding builds on studies that two 
related viruses, Ad-36 and Ad-5, also cause obesity in animals.

Moreover, Ad-36 has been associated with human obesity, leading 
researchers to suspect that Ad-37 also may be implicated in human 
obesity. Whigham said more research is needed to find out if Ad-37 
causes obesity in humans. One study was inconclusive, because only a 
handful of people showed evidence of infection with Ad-37 – not enough 
people to draw any conclusions, she said. Ad-37, Ad-36 and Ad-5 are part 
of a family of approximately 50 viruses known as human adenoviruses.

Researchers now must:

     * identify the viruses that cause human obesity
     * devise a screening test to identify people who are infected
     * develop a vaccine

Screening test and vaccine still a long way off

The Whigham et al. study prompted an editorial in the same issue of 
AJP-Regulatory, Integrative and Comparative Physiology by Frank 
Greenway, professor in the Department of Clinical Trials, Pennington 
Biomedical Research Center, Louisiana State University, Baton Rouge.

"If Ad-36 is responsible for a significant portion of human obesity, the 
logical therapeutic intervention would be to develop a vaccine to 
prevent future infections," Greenway wrote. "If a vaccine were to be 
developed, one would want to ensure that all the serotypes of human 
adenoviruses responsible for human obesity were covered in the vaccine."

"If one could predict the potential of an adenovirus to cause human 
obesity by using an in vitro assay or even by animal testing, screening 
of the approximately 50 human adenoviruses might be accelerated, 
shortening the time required for vaccine formulation," Greenway wrote. 
"Human antibody prevalence in obese and lean human populations appears 
to be the only reliable method to screen adenoviruses for their 
potential to cause obesity in humans at the present time," he noted.

Obesity contagion theory slow to catch on

The notion that viruses can cause obesity has been a contentious one 
among scientists, Whigham said. And yet, there is evidence that factors 
other than poor diet or lack of exercise may be at work in the obesity 
epidemic. "The prevalence of obesity has doubled in adults in the United 
States in the last 30 years and has tripled in children," the study 
noted. "With the exception of infectious diseases, no other chronic 
disease in history has spread so rapidly, and the etiological factors 
producing this epidemic have not been clearly identified."

"It makes people feel more comfortable to think that obesity stems from 
lack of control," Whigham said. "It's a big mental leap to think you can 
catch obesity." However, other diseases once thought to be the product 
of environmental factors are now known to stem from infectious agents. 
For example, ulcers were once thought to be the result of stress, but 
researchers eventually implicated bacteria, H. pylori, as a cause.

"The nearly simultaneous increase in the prevalence of obesity in most 
countries of the world is difficult to explain by changes in food intake 
and exercise alone, and suggest that adenoviruses could have 
contributed," the study said. "The role of adenoviruses in the worldwide 
epidemic of obesity is a critical question that demands additional 
research."

Ad-37 third virus implicated in animal obesity

The theory that viruses could play a part in obesity began a few decades 
ago when Nikhil Dhurandhar, now at Pennington Biomedical Research Center 
at LSU, noticed that chickens in India infected with the avian 
adenovirus SMAM-1 had significantly more fat than non-infected chickens. 
The discovery was intriguing because the explosion of human obesity, 
even in poor countries, has led to suspicions that overeating and lack 
of exercise weren't the only culprits in the rapidly widening human 
girth. Since then, Ad-36 has been found to be more prevalent in obese 
humans.

In the current study, Whigham et al. attempted to determine which 
adenoviruses (in addition to Ad-36 and Ad-5) might be associated with 
obesity in chickens. The animals were separated into four groups and 
exposed to either Ad-2, Ad-31, or Ad-37. There was also a control group 
that was not exposed to any of the viruses. The researchers measured 
food intake and tracked weight over three weeks before ending the 
experiment and measuring the chickens' visceral fat, total body fat, 
serum lipids, and viral antibodies.

Chickens inoculated with Ad-37 had much more visceral fat and body fat 
compared with the chickens infected with Ad-2, Ad-31 or the control 
group, even though they didn't eat any more. The Ad-37 group was also 
generally heavier compared to the other three groups, but the difference 
wasn't great enough to be significant by scientific standards.

The authors concluded that Ad-37 increases obesity in chickens, but Ad-2 
and Ad-31 do not. "Ad-37 is the third human adenovirus to increase 
adiposity in animals, but not all adenoviruses produce obesity," the 
study concluded.

There is still much to learn about how these viruses work, Whigham said. 
"There are people and animals that get infected and don't get fat. We 
don't know why," she said. Among the possibilities: the virus hasn't 
been in the body long enough to produce the additional fat; or the virus 
creates a tendency to obesity that must be triggered by overeating, she 
said.

Mass screening for these viruses is impractical right now because there 
is no simple blood test available that would quickly identify exposure 
to a suspect virus, Whigham et al. said. More work is needed to develop 
such a test, Whigham said.

###

Source, funding and disclosure

"Adipogenic potential of multiple human adenoviruses in vivo and in 
vitro in animals," by Leah D. Whigham and Richard L. Atkinson of the 
Departments of Medicine and Nutritional Sciences at the University of 
Wisconsin, Madison, and Barbara A. Israel of the Department of 
Pathobiological Sciences, University of Wisconsin, Madison, is in the 
January issue of the American Journal of Physiology - Regulatory, 
Integrative and Comparative Physiology published by the American 
Physiological Society.

Research was supported by grants from the National Institute of Diabetes 
and Digestive and Kidney Diseases, and the Beers-Murphy Clinical 
Nutrition Center, University of Wisconsin. Atkinson, now at the Virginia 
Commonwealth University, owns all shares of Obetech LLC, a company that 
markets assays to detect infection with human adenovirus-36 and owns 
patent rights for these assays.

Editor's note: The media may obtain a copy of Whigham et al. by 
contacting Christine Guilfoy, American Physiological Society, 
301-634-7253 or cguilfoy at the-aps.org.

The American Physiological Society was founded in 1887 to foster basic 
and applied bioscience. The Bethesda, Maryland-based society has more 
than 10,000 members and publishes 14 peer-reviewed journals containing 
almost 4,000 articles annually.

APS provides a wide range of research, educational and career support 
and programming to further the contributions of physiology to 
understanding the mechanisms of diseased and healthy states. In May 
2004, APS received the Presidential Award for Excellence in Science, 
Mathematics and Engineering Mentoring (PAESMEM).
-- 
Kathrynne Holden, MS, RD < fivestar at nutritionucanlivewith.com >
"Ask the Parkinson Dietitian"  http://www.parkinson.org/
"Eat well, stay well with Parkinson's disease"
"Parkinson's disease: Guidelines for Medical Nutrition Therapy"
http://www.nutritionucanlivewith.com/