The present report, compares two murine models of virus induced chronic relapsing demyelination. MHV-induced demyelination in the BALB/c mouse results from the direct virus mediated cytolysis of oligodendrocytes. Extensive remyelination by oligodendrocytes is noted. Recurrent demyel- ination occurs in small areas. Infectious virus persists and 34 Fig. 2: Demyelination in SJL/J mice infected with TMEV. A) Multifocal areas of perivascular demyelination in the spinal cord (110 days post infection). Para- phenylene diamine stain. X 250. B) Perivascular inflammatory infiltration within the white...