Recent genetic evidence points towards endogenous retroviruses as playing a pivotal role in the causation of multiple sclerosis and possibly other autoimmune diseases. We discuss various ways in which this association could be brought about. Specifically, we suggest that two endogenous retroviruses, HERV-Fc1 and HERV-K13, on chromosomes X and 19, respectively, contribute to the development of autoimmune T cells by transforming them in multiple sclerosis. Partially overlapping sets of endogenous retroviruses may play a role in other autoimmune diseases. If this theory holds true, many scientists may have looked for viruses in the wrong tissue. Ir would also explain why lymphocyte-suppressive agents suppress multiple sclerosis.
Keywords: Autoimmune diseases; Endogenous retroviruses; Multiple sclerosis.