Virus-induced demyelination in man: models for multiple sclerosis.

Epidemiologists have long worked at the limit of their powers to invoke an infectious agent to explain some of the epidemiological features of multiple sclerosis (MS). No virus has yet been definitively assigned a causal role in the pathogenesis of MS. Many viruses, however, have been incriminated, but it has not been possible to reproduce every single observation. Nevertheless, important lessons have been learned from the quest to identify such agents. Other kinds of demyelinating disease within the central nervous system (CNS) have been clearly linked to direct or indirect effects of viral infection. An understanding of the pathogenesis of these models affords possible insights into the mechanisms by which viruses or other agents might be operative in MS and other chronic diseases of the nervous system.