Virus and demyelination why suspect that a virus maybe involved in the aetiology of multiple sclerosis?

Introduction. Epidemiological data indicate that environmental factors, possibly infections, are associated with the development of multiple sclerosis. Different viruses are known to produce demyelination in natural and experimental animal infections. In humans some virus cause acute or chronic diseases that course with central nervous system demyelination. A series of virus have been claimed to be etiological agents of multiple sclerosis, although a causal role for any of them has so far been demonstrated. Method The mechanisms of viral demyelination are diverse, ranging from direct destruction of infected oligodendrocytes to triggering autoimmune responses without virus multiplication in target cells. The potential indirect mechanisms of viral demyelination and the heterogeneous histopathology shown in multiple sclerosis patients, suggesting an heterogeneus etiology, might explain why not a single virus has been as yet identified as the cause of this disease. Conclusions. Viral infections that cause demyelination in animals and humans are briefly reviewed, focusing on the potential myelin destruction mechanisms and obstacles to the identifying viruses that might cause multiple sclerosis.