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Infectious Obesity (video)
July 05, 2001
Also on ScienCentral News
This Little Virus - The announcement of a new cloned pig this week is being hailed as a major step toward the use of animal organs in human transplants. But do pig organs carry a dangerous virus that could spread in human patients? A new study also out this week says that threat is real. (8/22/00)
Fat Virus - Scientists have found a virus that causes obesity. (7/27/01)
Elsewhere on the web
Prevalence of Overweight and Obesity Among Adults: United States, 1999
Controlling the Global Obesity Epidemic
Obesity epideminc threatens health in exercise-deprived societies - press release from the Worldwatch Institute
Obesity Epidemic Increases Dramatically in the U.S. - news release from the CDC
Is obesity infectious? Scientists showed last year that a human virus could cause obesity in animals. But they did not know if the virus could be transmitted from one animal to another.
But as this ScienCentral News video reports, researchers have now shown that the fat virus is contagious.
Further Q&A with Nikhil Dhurandhar
How infectious is the virus?
"When chickens are two to a cage, with one infected with the virus, the viral DNA appears in the blood of the cagemate within 12 hours. It continued to be there for 25 days, the length of the experiment. Even more important, we infected chickens with the virus (put it in their nostrils) and within 36 hours took their blood. Of course, we found the virus, but also, like a blood transfusion, we gave the blood to a new set of animals (we also did this with control animals). One, there was virus in the blood drawn after 36 hours. Two, the virus could be transmitted from the infected donors. Three, the infected donors and the receivers both got obese.
"This is very important because we fulfilled Koch’s Postulate. Koch’s Postulate was formulated by Robert Koch more than a hundred years ago; he listed five criteria for demonstrating that a particular agent causes a particular disease. He basically said, If and only if you can give it to an animal and produce the disease in that animal, then take their blood and inject it into a new set of animals and they also get the disease, then I’ll believe that agent causes that disease."
How does this virus cause obesity?
"We have presented our thoughts on the mechanism in abstract form at conferences but it has not yet been published. We think the mechanism is, it causes fat cell differentiation. Before fat cells become adipocytes, they are pre-adipocytes. The process is called differentiation. The number of pre-adipocytes that differentiate into adipocytes increases three-fold by this virus. We need to find out: What genes is it upregulating or turning off?"
So can it cause obesity in humans?
"We still can’t say. You can’t infect people [for a study], so it is always going to be circumstantial evidence. We have continued screening people for antibodies to the virus and are finding a strong association with obesity and having the same low cholesterol and low triglycerides we find in animals. (See ScienCentral News’s "Fat Virus") The point is not to worry about one virus; we need to look for similar pathogens contributing to obesity. We won’t find them if we’re not looking for them."
