ABSTRACT
Theiler's murine encephalomyelitis virus (TMEV)-induced demyelination and experimental allergic encephalomyelitis are the principal immunologically mediated, genetically controlled models of multiple sclerosis. Previous studies using different mapping techniques identified susceptibility loci for both diseases on chromosomes 3, 6, and 17. To more precisely map these TMEV and experimental allergic encephalomyelitis loci relative to each other, linkage analysis using microsatellite markers and a (BALB/cByJ x DBA/2J) x BALB/cByJ backcross population segregating for TMEV-induced disease was conducted. Comparisonwise and chromosomewise critical values based on permutation theory were estimated for each chromosome. Evidence for linkage to markers on chromosome 17 was not seen. Chromosomewise linkage (p = 0.13) was detected with D6 Mit36 and D6 Mit149 (marker-specific chromosomewise p values = 0.02) at 40.4 cM on chromosome 6. Chromosomewise linkage (p < 0.01) (marker-specific chromosomewise p value = 0.0) and comparisonwise linkage (p < < 0.0001) to D3 Mit156 at 33.9 cM on chromosome 3 were observed along with chromosomewise linkage (p < 0.05) and comparisonwise linkage (p < < 0.0001) to D3 Mit29, D3 Mit311, D3 Mit28, and D3 Mit11 from 33.9 to 37.2 cM, respectively. Significant linkage to D3 Mit156 places Tmevd2 1.1 cM proximal of D3 Mit101 (35 cM), the maximally linked marker to the eae3 susceptibility gene. Maximum likelihood estimates conducted by multilocus linkage analysis localized Tmevd2 within a 95% confidence interval bordered by D3 Mit29 and D3 Mit10, at 33.9 and 37.2 cM, respectively. Taken together these results suggest that Tmevd2 and eae3 may represent either a single, common susceptibility gene or members of a gene complex involved in central nervous system immunopathology.
