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Back To Vidyya Vaccine Could Prevent Type I Diabetes

Vaccine Could Be Applied To Intervene For High-Risk Individuals

A vaccine that would inhibit the onset of Type I diabetes -- insulin dependent diabetes -- could be on the horizon for those at high risk of developing the disease, researchers at North Carolina at Chapel Hill said Wednesday.

"Our study indicates that a vaccine could be applied to intervene for high-risk people to block the auto-immune process to prevent the onset of Type 1 diabetes," said Dr. Roland Tisch, of the Chapel Hill Medical School. A report of the research appears in the Feb. 1 issue of the Journal of Immunology.

Type I diabetes, also known as juvenile diabetes, results from an auto-immune response -- the body destroys the cells needed to produce insulin. It's mostly diagnosed in adolescents but can be found in young adults as well. Type II diabetes is found mostly in older adults who produce less insulin and is considered a metabolic disease.

The North Carolina researchers used plasmid DNA that would inhibit development of insulin-dependent diabetes. Plasmid DNA is circular genetic material obtained from bacteria and therefore plentiful. "Plasmid DNA functions as a scaffold that genes of interest are inserted," Tisch explained. "In the past, our group and others could manipulate the damaging auto-immune response in various animal models for Type I diabetes but not in ways that would be readily feasible clinically."

Tisch used the genetic vaccine to re-establish the natural balance between two kinds of immune cells -- Th1 cells and Th2 cells. When misbehaving, and researchers still don't know why, the former attack the critical insulin-producing islet beta cells. When Th2 cells fail to do their job, Th1 cells eventually lead to Type I diabetes.

"Our approach was relatively simple," Tisch said. "The vaccines allowed us to selectively suppress the body's auto-immune response while leaving the remainder of the immune response intact."

Tisch and his colleagues engineered their vaccines to express two different proteins -- one that activated T cells that recognize islet beta cells and another that boosted those T cells to develop into Th2 cells needed to hold Th1 cells in check.

"One of the appealing features of plasmid DNA vaccines is that the DNA persists for long periods," Tisch said. "We gave our mice three injections in three weeks, and the majority of the animals have remained diabetes-free for more than a year -- mice have a lifespan of about two years." Ideally, human patients might require injection of plasmid DNA vaccines only every year or two, according to Tisch.

"The study clearly demonstrates that only a few injections of the genetic vaccine could prevent the onset of insulin-dependent diabetes," Dr. Alex Rabinovitch, of the University of Alberta, in Canada, told UPI. "This research advance is important because the type of vaccine developed in human subjects at high-risk for Type I diabetes."

Those considered at high-risk for diabetes are those who have a first-degree relative with Type I diabetes, test positive for certain antibodies and test positive for poor insulin response to glucose.

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Editor: Susan K. Boyer, RN
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