The transgene comprises, in order, a 1.3 kb fragment of the mouse myelin basic protein (Mbp) gene that includes the promoter, mRNA cap site and 5' noncoding sequence; a mouse Mbp cDNA containing the full coding sequence for the smallest (14kDa) MBP protein; the 760 bp third exon of the mouse prion protein (Prnp) gene - which contains the entire Prnp open reading frame - flanked by two copies of the rabbit beta-globin second intron; and polyadenylation signals from the rabbit beta-globin and SV40 early region genes. (J:97275)