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.
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.
Christine Guilfoy | EurekAlert!
Team discovers how bacteria exploit a chink in the body's armor
20.01.2017 | University of Illinois at Urbana-Champaign
Rabies viruses reveal wiring in transparent brains
19.01.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences