Theiler's virus persists in glial cells during demyelinating disease.

Theiler's murine encephalomyelitis virus (T-MuEV) is the agent of a persistent, demyelinating infection of the central nervous system of mice, T-MuEV RNA was detected in histological sections of brain and spinal cord of experimentally infected animals by in situ hybridization. Both neurons and glial cells contained viral RNA during the early acute phase of the disease, The amount of viral RNA in neurons, however, was considerably higher than in glial cells. During the late demyelinating phase of the disease, viral RNA was found in low amounts only in glial cells of the white matter of spinal cord. At that stage, no viral RNA was found in neurons. These results demonstrate that T-MuEV persists in glial cells of the white matter. A reconstruction of the pathogenesis of this persistent infection is proposed, based on the different levels of virus replication in neurons and glial cells.