
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: FRIDAY, November 25, 1994                   TAG: 9411250036
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A-2   EDITION: METRO 
SOURCE: Associated Press
DATELINE:                                 LENGTH: Medium

VIRUS IS IMPLICATED AS CAUSE OF DIABETES

Researchers in California and Florida have produced strong new evidence implicating a common class of viruses in causing Type 1 or insulin-dependent diabetes, a discovery that could eventually lead to new ways of preventing the disease that affects as many as 1 million Americans.

Type 1 diabetes occurs when the body's immune system attacks and destroys insulin-producing cells in the pancreas. Researchers know that only people with a specific genetic profile are susceptible to this auto-immune attack, but there has been great debate about the identity of the agent that triggers the immune reaction.

Now, two studies in this month's issues of the Journal of Experimental Medicine and the Journal of Clinical Investigation strongly implicate Coxsackie viruses, polio-related viruses that cause upper respiratory infections.

One report shows that Coxsackie viruses trigger diabetes in genetically susceptible mice but not in those that have a different genetic profile. The second demonstrates that the auto-immune reaction is triggered by a similarity between a Coxsackie virus protein and a protein in the pancreas.

The two studies provide ``a strong case of guilt by association,'' said molecular biologist Daniel L. Kaufman of the University of California, Los Angeles.

``It's only inferential data so far, but it's pretty strong inferential data,'' added Dr. Noel Maclaren of the University of Florida. ``I think the case is really seriously beginning to build'' that Coxsackie viruses are the key triggering agent.

If the virus is shown to be a primary cause of the disease, vaccines against the virus could probably prevent diabetes, the researchers said. But ``before we can start working on such a vaccine, we need to have a fairly clear smoking gun,'' strongly confirming that the virus causes diabetes, said Dr. Joan Harmon, director of the Diabetes Research Program at the National Institutes of Health.

Researchers have a 30-year history of interest in Coxsackie viruses as a diabetes cause. Epidemiological studies in the 1960s, for example, showed that Coxsackie outbreaks in various regions were followed by an increased incidence of diabetes. Studies also showed that perhaps 60 percent of newly diagnosed diabetics had antibodies to the virus.

More recently, researchers such as Maclaren and his Florida colleague Mark Atkinson have demonstrated that people in the very earliest stages of diabetes have antibodies against a specific protein, subsequently shown by Kaufman and others to be an enzyme called glutamic acid decarboxylase or GAD.

Three years ago, Kaufman and Allen J. Tobin of UCLA demonstrated that a small segment of an enzyme called GAD is structurally similar to a segment of a Coxsackie protein. Their interpretation was that when the immune system attacks this viral protein in fighting off a Coxsackie infection, it also inadvertently attacks GAD, which is found on the surface of insulin-secreting pancreas cells. Ultimately the cells are destroyed and diabetes results.

by CNB