Susceptibility to Theiler's virus-induced demyelination. Mapping of the gene within the H-2D region

Demyelination induced by Theiler's virus was examined in mouse strains with congeneic recombinant haplotypes. Light and electron microscopy of spinal cord sections from mice with s, q, v, p, and f H-2D alleles showed perivascular inflammation and primary demyelination. The presence of susceptible haplotypes in the K or I region did not correlate with pathologic abnormalities. The Qa, Tla, PgK, and UpG genes did not appear to be critical in determining susceptibility to disease. However, mutation in the H-2D genes altered the susceptibility to virus-induced demyelination. B10.D2dm1 mice, which have deletions in the 3' end of Dd and the 5' end of Ld, showed prominent demyelination and clinical deficits. In contrast, BALB/c-dm2, which have a deletion of the entire L gene, showed no pathologic changes. Central nervous system virus titers correlated with susceptibility to demyelination; both resistant and susceptible strains had a strong humoral immune response to the virus. The findings in the congeneic recombinant mice and in mice mutant in the H-2D region strongly suggest that at least one of the genes critical for determining virus-induced demyelination maps to the 3' end of the H-2D gene.