MOLECULAR ANALYSIS OF THE DLA DR REGION

The dog is an important model for studying organ transplantation. In o rder to develop a DNA-based typing system, a genomic analysis of the c anine DR region of the MHC was undertaken. Southern analysis suggests the presence of two DRB genes in most dogs and all have one DRA gene. One dog out of 200 examined contains only one DRB gene. The DRA gene w as mapped in one lambda phage clone. One DRB gene (DRBB1) was localize d to two overlapping phage clones. Another DRB gene (DRBB2) was locali zed to two overlapping phage clones. Sequence analysis of the two DRB genes suggests that one gene is intact (DRBB1) and one gene is a pseud ogene (DRBB2) because it lacks a splice acceptor signal for exon 3 and lacks exons 2 and exon 4. Intron 1 and 2 sequence data from DRBB1 all ow amplification of the polymorphic exon 2 which, in turn, can serve a s a basis for developing a typing system for DRB.