Studies point to viruses as cause of diabetes

LONDON Thu Mar 5, 2009 2:04pm EST

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LONDON (Reuters) - Two studies published on Thursday provide evidence that common viruses may cause childhood diabetes, paving the way for potential vaccines against the life-threatening condition, researchers said.

One team showed that enteroviruses -- which normally cause colds, vomiting or diarrhea -- were found frequently in the pancreases of young people who had recently died from type 1 diabetes, sometimes called juvenile diabetes, but not in healthy samples.

This suggests a virus could trigger the disease in children genetically predisposed to the condition, which affects an estimated 440,000 people worldwide, said Alan Foulis of the Royal Infirmary in Glasgow, who worked on one of the studies.

"The story that is emerging is there is a virus infection that precedes the onset of autoimmunity," he told a news conference. "There is a thought that we are looking at the culprit."

Type 1 diabetes is caused by the destruction of beta cells of the pancreas that produce the insulin necessary to regulate blood sugar levels. The autoimmune disease is different from the far more common type 2 diabetes, which is strongly associated with obesity.

Genetics play a role in diabetes but researchers know other factors such as diet are also important, with viruses long suspected as a possible trigger, researchers said.

Foulis and colleagues examined 73 pancreas samples of young people who had died from diabetes and found that 60 percent of the donated organs contained evidence of enteroviral infection of beta cells.

By contrast, the researchers hardly ever saw infected beta cells in tissue samples taken from 50 children without diabetes, they reported in the journal Diabetologia.

They also found a large proportion of these infected cells in adults with the more common type 2 diabetes, suggesting that viruses may also trigger this form of the disease in some people.

A second study from Cambridge University researchers found that rare genetic mutations in a gene involved with the body's response to viruses reduce the risk of juvenile diabetes.

They looked at 480 young people with type 1 diabetes and another 480 healthy people to identify the gene and the variants involved.

"We have pinpointed a specific gene, which acts as a warning report for virus infection," John Todd, a Cambridge University researcher, who worked on a study published in the journal Science. "Not only have we found a specific gene but this gene also has an intriguing function in dealing with virus infection."

While Todd cautioned that many environmental factors besides viruses could contribute to type 1 diabetes, Foulis and his team said they wanted to whittle down the some 100 enteroviruses to find which ones played the main roles.

Doing this, and better understanding of how cells respond to viral infection, are steps toward a vaccine that could one day protect children against diabetes, Foulis said.

"The aim would be for a vaccine that would prevent many cases of type 1 diabetes," he added.

(Reporting by Michael Kahn, Editing by Will Dunham and Richard Williams)

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