Swan mice: autoimmune mice without xenotropic type C virus production.

Swan mice are characterized by various autoimmune disorders and the Swan disease resembles that of (NZB X NZW)F1 hybrids. A virological study of these animals shows that: (a) they do not produce xenotropic type C viruses at a detectable level; (b) old Swan mice can produce ecotropic type C virus but at a low level; and (c) this virus production and the appearance of antinuclear antibodies are dissociated in some mice. These results do not support the role of xenotropic type C viruses in murine autoimmune pathology. A possible role of ecotropic type C viruses cannot be definitely excluded, but appears unlikely.