Virological and immunological aspects of coronavirus induced subacute demyelinating encephalomyelitis in rats.

Infection of rats with the murine coronavirus JHM led to acute or subacute encephalitis. Viral and host factors greatly influenced the outcome of the infection. A number of temperature-sensitive (ts) mutants was obtained which differed widely in their capacity to induce lesions of the central nervous system (CNS) in rats. Under defined conditions a subacute demyelinating encephalomyelitis ( SDE ) with pronounced clinical signs was observed 14-160 days post infection (p.i.). A number of rats, which showed a remission of SDE later developed a relapse of the disease accompanied by neurological symptoms. Neuropathological examination of such animals revealed lesions of active demyelination and extended remyelinated areas. The presence of viral antigen or infectious virus in the CNS of these rats demonstrated that they were persistently infected. Further investigations indicated that this virus infection triggers a cell mediated immune response against basic myelin protein which may contribute to the development of subacute to chronic encephalomyelitides .