MAPPING OF THE SLA COMPLEX CLASS-III REGION BY PULSED-FIELD GEL-ELECTROPHORESIS

The fine order of genes in the class III region of the swine major his tocompatibility complex (MHC), the SLA complex, was examined by pulsed field gel electrophoresis (PFGE) and Southern blot analysis. Four gen es, C2, HSP70, TNF alpha, and CYP21, were analyzed. The CYP21, C2, and HSP70 genes were all located within a 200-kb NotI fragment. The C2, H SP70, and TNF alpha genes cohybridized to a 420-kb SalI fragment. The TNF alpha gene is linked to the class I region by a 390-kb NotI fragme nt. Combined with a previous study from our lab, the order of genes in the SLA complex is class II-class III [(CYP21/C4)-(Bf/C2/HSP70)-TNF a lpha]-class I. The size of the class III region from CYP2I to TNF alph a is estimated to be 500 kb. This size and the order of the genes in t he swine class III region are similar to those of human, mouse, goat, and rabbit, which confirms the high conservation of class III gene org anization across species.