25 February 2003 15:00 GMT

by Alexandra Venter

The advent of proteomics and novel molecular techniques could finally reveal the notoriously elusive cause of multiple sclerosis (MS), say researchers. But until a cause - bacterial, virological or genetic - has been definitively pinpointed, an effective vaccine remains a distant goal.

"Times are ripe" for a major breakthrough in MS research, says William Cafruny, professor of immunology at the University of South Dakota School of Medicine. Scientists have speculated about the role of infection in the etiology of the disease for over a century. The extent to which genetic susceptibility plays a part is also unclear, says Cafruny. "[MS is] a very elusive disease process that modern tools of molecular biology and proteomics will likely reveal," he predicted.

Studies of people who have migrated from one environment to another support the notion that MS results from a childhood infection. Post-adolescent migrants who emigrate from MS hot spots to low risk areas take with them the higher risk of developing MS. Those leaving low risk regions and moving to places where MS is more prevalent maintain the lower risk.

Among the many candidates for infectious agents of MS is the tick-borne bacterium Borrelia burgdorferi, which also spreads Lyme disease. An autoimmune response stemming from exposure to bacterial proteins is one explanation for the cause of the disease, and some researchers suspect that maternal exposure to the bacterium causes the unborn child to develop MS later in life. To confuse this link, however, Lyme disease is sometimes mistaken for MS.

Viral candidates include Human Herpesvirus-6 and Epstein-Barr virus, although the serological data on each remain controversial. Both viruses deserve more study, says Cafruny.

Current drug treatments for MS do not reveal the cause of the disease. Intravenous immunoglobulin (IVIG) treatment, for example, might fight viral infection by providing the necessary antibodies. Alternatively, the apparent success of IVIG in treating MS might lie in the ability of the treatment to reduce myelin damage due to inflammation. Likewise, any therapeutic success with interferon-beta might result from interference with viral replication, or simply downregulation of the patient's immune response.

MS research must also focus on immune processes, myelin re-growth and repair, and genetic susceptibility, says Deanna Groetzinger of the MS Society of Canada. The prevalence of MS in Canada is high, reaching 248 per 100,000 in Saskatoon, Saskatchewan, the highest reported rate of MS in the world, according to a review by Giulio Rosati in the journal Neurological Sciences.

The impact of the disease is especially devastating, says Groetzinger, because MS often strikes young adults who are raising families. While Groetzinger values efforts to pin down an infectious agent, she points to the fact that in some groups living in high-risk regions, such as Aboriginal Canadians, MS rarely, if ever, occurs.

If clear evidence finally implicates a viral candidate, says Cafruny, a vaccine could be developed quickly. However, he says, drug companies will not be prepared to make a vaccine based on current data.

Printer ready version
E-mail article to a friend

 

See also:
The role of macrophage/microglia and astrocytes in the pathogenesis of three neurologic disorders...
Alireza Minagar, Paul Shapshak, Robert Fujimura, Ray Ownby, Melvin Heyes and Carl Eisdorfer
Macrophage/microglia are the principal immune cells in the central nervous system (CNS) concomitant with inflammatory brain disease and play a significant role in the host defense against invading microorganisms.
Journal of the Neurological Sciences, 2002, 202:1-2:13-23

Chlamydia pneumoniae and multiple sclerosis: no significant association [Research news]
Jean C. Tsai and Donald H. Gilden
The cause of multiple sclerosis (MS) is unknown. Despite indications from epidemiological and identical-twin studies that MS is infectious, no virus or other infectious agent has been tightly linked to...
Trends in Microbiology, 2001, 9:4:152-154

Viral-induced neurodegenerative disease [Review article]
Michael J Buchmeier, Thomas E Lanev
Current Opinion in Microbiology 1999, 2:398-402.
 

Printer ready version
E-mail article to a friend