An experimental therapeutic vaccine appears to produce beneficial changes in the immune systems and brains of those living with multiple sclerosis, finds a study in Archives of Neurology.

An estimated 55,000-75,000 Canadians have multiple sclerosis. It causes symptoms that include blurred vision, loss of balance, poor co-ordination, paralysis and blindness.

The cause is unknown, but evidence suggests the immune system of MS patients attacks the myelin that covers and protecta nerve cells in the brain and spinal cord.

A research team led by Montreal neuroimmunologist Dr. Amit Bar-Or tested the effectiveness of a vaccine, called BHT-3009, that incorporates the DNA sequence of myelin basic protein into cells, which then start to make the protein.

Bar-Or's team administered the therapeutic vaccine to 30 MS patients during a two-year period. The patients had either relapsing-remitting MS, marked both by periods suffering symptoms of the disease or in remission, or secondary progressive MS, in which symptoms worsen, but there are still periods of remission.

"BHT-3009 was safe and well tolerated, provided favorable trends on brain MRI and produced beneficial antigen-specific immune changes," the authors write.

The vaccine reduced the number of cytokine-producing CD4+ T cells -- a type of white blood cell that specifically targets myelin proteins. As well, the researchers noted a decrease in the number and volume of lesions in the brain in patients treated with BHT-3009. The development of lesions is used to measure MS activity in patients.

"There were no increases in clinical relapses, disability, drug-associated laboratory abnormalities, adverse events or the number and volume of contrast-enhancing lesions on brain MRI with BHT-3009 treatment compared with placebo," the authors wrote.

Bar-Or says while the results are promising, the study of the vaccine is in its early phases. The main purpose of this trial was to assess the vaccine's safety.

A larger, second phase of the study into BHT-3009 is already underway. The vaccine's manufacturer, Bayhill Therapeutics, a California-based biotechnology company, is paying for both studies.

The researchers say if it all goes well, that it's possible that antigen-specific DNA vaccines could one day be developed for treatment of related diseases, such as type 1 diabetes, lupus and rheumatoid arthritis.