Study tests whether virus triggers MS
The common cold — inconvenient and annoying but generally considered benign — may cause attacks of multiple sclerosis. And it may provide a clue about what causes MS in the first place.
That's the premise of a study being launched at the University of Utah School of Medicine, which is seeking help from local MS patients. Several thousand Utahns are estimated to have the disease.
Researchers have previously noticed that while MS patients may be less likely than other people to get a cold in the first place, a worsening of MS symptoms is three to four times more likely when they do catch a cold. Multiple sclerosis typically waxes and wanes in patients with the "relapsing-remitting" form of the disease, which accounts for 80 percent of all MS cases.
It's possible that a cold virus is also the "inciting agent" for the initial development of MS, says Dr. John D. Kriesel, the study's principal investigator and an assistant professor of internal medicine and infectious diseases. The cause of the debilitating disease, which damages the brain and spinal cord, has long been a mystery.
The goal of the study, which will be conducted by the U., Salt Lake City Veterans Administration Hospital, ARUP Laboratories and the University of Arizona, is to identify which specific viruses, if any, might be triggering an MS attack. These viruses could then be targeted by vaccines or treated with anti-viral drugs. Participants, each with active colds that have lasted no more than a day or two, will provide samples of blood and nasal mucous, and undergo a neurological examination. One or more additional visits will be required over a subsequent five-week period.
The possible link between colds and MS was first discovered in 1985 by University of Arizona neurology professor William Sibley, who will be a co-investigator in the current study. The new study will use sophisticated molecular-biology techniques to parse out which particular cold viruses might be to blame, Kriesel says.
Previous research pointing to a virus as the trigger for the initial disease and subsequent attacks includes the fact that outbreaks are often seasonal. The studies also show that disease occurs more often in people who were born in the spring rather than the late fall.
"I would say it has something to do with maternal antibodies and resistance to viral infection," Kriesel said. Children born in the spring eventually lose the protection of their mother's antibodies within the first nine months, he said. By then it's winter or early spring, when they may be susceptible to a cold virus. Re-exposure to that virus or a similar virus may lead to MS.
Kriesel cited the work of John Kurtzke, which provides evidence that a "priming infection" is acquired before puberty. Migration studies have borne this out, he says. For example, a person born in Africa who moves to Sweden at age 15 has a low chance of acquiring MS, whereas a person born in Sweden, where cold viruses are more prevalent, and then moves to Africa, has a much higher chance of having MS.
An outbreak of MS in the Faroe Islands in 1943 also points to the virus hypothesis, he says. The outbreak on the remote island occurred after the British arrived in 1940.
It's possible, though, that it's not the cold virus itself but rather "the nastiness of having the cold" that triggers MS attacks, Kriesel says. "A lot of researchers have given up on the viruses. They've tried to grow viruses out of the brains of MS patients and haven't succeeded."
Source: Deseret News.com © 2006 Deseret News Publishing Company