Canine distemper virus-specific antibodies in multiple sclerosis.

Current postulates support the idea that MS is triggered by an infectious agent or agents through an autoimmune reaction directed against brain antigens in genetically susceptible individuals. Evidence for an infectious etiology of MS is indirect. We have proposed that MS may, in some instances, be due to a zoonotic infection and that canine distemper virus, a measles-like virus in dogs, is a likely candidate in the causation of this disorder. The high homology between canine distemper and measles virus proteins has made it extremely difficult to distinguish distemper from measles antibodies serologically. We now provide evidence that humans can be infected with this neurotropic dog virus. Furthermore, a high titer of canine distemper virus antibodies is significantly associated with MS. Identification of the etiologic agent in MS may lead to the elucidation of disease pathogenesis and to disease prevention through appropriate public health and vaccination programs.