The possible viral aetiology of disseminated sclerosis.

The two most attractive current hypotheses concerning the aetiology of disseminated (multiple) sclerosis (MS) are those of (1) an 'autoimmune' process, analogous to experimental allergic encephalitis, or (2) an infection, for which the 'slow virus diseases' of the central nervous system represent a possible model. Experimental data have been advanced favouring each hypothesis, and it is in fact quite possible that both mechanisms may have a contributing role. Our purpose in this presentation will be to discuss only the infectious hypothesis, and more particularly the possibility of a virus aetiology. However, whether or not one or a combination of viruses is implicated in the pathology of MS, it appears that immunopathological events must be considered to explain the clinical evolution of the disease.