Viruses And Demyelination

Multiple sclerosis (MS) has been recognized as a distinct clinical entity for over 100 years, but its etiology remains elusive. In all likelihood, a viral infection during childhood or adolescence triggers an autoimmune response to oligodendrocytes and/or myelin in susceptible individuals (1). Patients with MS are now being treated with cyclophosphamide (2, 3), cyclosporine (4), azathioprine (5), whole body radiation (6, 7), or plasmapheresis (8), on the assumption that MS is an autoimmune disease. These therapies have potentially serious hematologic, gastrointestinal, infectious, or neoplastic side effects (9). Immunosuppressive therapy, even if effective in stabilizing multiple sclerosis, is less than ideal because of the above mentioned side effects. Establishment of the etiology of MS may allow for more earlier, more specific, and less toxic treatment. In this paper we will review the epidemiologic evidence for a viral etiology of MS, the current state of candidate viruses, viral associated human demyelinating diseases other than MS, and the animal models of viral-induced demyelination.