Demyelinating lesions due to Theiler's virus are associated with ongoing central nervous system infection.

We used in situ hybridization and immunocytochemistry to look for a correlation between virus expression and white matter lesions during late demyelinating disease due to persistent Theiler's virus infection. We found the following. (i) Tissue lesions developed at the site of virus infection. This correlation was not explained by infection of lymphocytes and macrophages. (ii) Large differences in the extent of pathology existed between mice. The amount of inflammation paralleled the number of cells containing viral RNA or viral capsid antigens. (iii) C57BL/6 mice, which are resistant to demyelination, were able to eradicate the infection. Our results are strongly in favor of a mechanism of demyelination in which viral gene products play a central role.