-Source: LaJolla Institute for Allergy & Immunology, November 2, 2004 Researchers at the LaJolla Institute for Allergy and Immunology have found that, while viruses alone do not initiate autoimmune diseases, they can accelerate their development when paired with a genetic predisposition to autoimmune diseases. This discovery, based on controlled laboratory studies of mice, represents the first demonstration in a living organism of the ability of viruses to increase the likelihood of the development of autoimmune diseases. The finding, published November 1, is an important advance that could help in the future development of therapies for the treatment or prevention of diabetes and other autoimmune illnesses.

The research team, headed by Matthias von Herrath, M.D., focused on a concept known as "molecular mimicry" or cross-reactivity. This occurs when the body immune system recognizes not only part of a virus but also a molecule in the body that looks very similar and begins attacking cells that have that molecule assuming it is an actual virus.

"We knew from evidence that cross-reactivity is common," Dr. Von Herrath said, "but what we didnt know was whether that could actually accelerate the development of autoimmune disease in some individuals." He added that it has long been theorized to play a role. "We found that it is unlikely that this cross-reactivity causes disease in someone who is not genetically predisposed to an autoimmune disease," he said. "However, if you superimpose cross-reactivity to a virus onto a genetic predisposition to an autoimmune disease, then it is much more likely that youll develop the disease--and it happens faster."

Dr. Von Herrath stated that the finding opens the door to further research to find associations between certain viruses and certain genetic predispositions to autoimmune diseases. He said that this could shape large scale clinical studies of people with existing autoimmune diseases to identify, through their medical histories, which viruses, when paired with which genetic predispositions, can cause certain autoimmune diseases to erupt.