An experimental DNA vaccine against multiple sclerosis (MS) appears safe in early human tests and shows signs of effectiveness, according to a paper published Monday in the online version of the Archives of Neurology.

In MS, the immune system attacks the fatty coating, known as myelin, protecting nerve cells in the brain and spinal cord, eventually destroying nerve cells' ability to communicate. The cause of the disease is unknown.

In the study, headed by Amit Bar-Or of the Montreal Neurological Institute in Canada, patients were given a vaccine made up of one of the protein components of myelin. The idea is that the vaccine will damp the body's tendency to attack myelin.

While larger studies are needed to determine if the vaccine will truly help MS patients, initial results were promising. The vaccine appears safe and showed early signs of a beneficial effect on the immune system: the number of immune cells in the spinal fluid that attack myelin was reduced in a small subset of patients who underwent lumbar puncture. A larger study of the vaccine is now under way.