A first map of the porcine major histocompatibility complex class I region

A map of the SLA complex, or swine major histocompatibility complex (MHC), class I region was constructed by alignment of yeast artificial chromosomes (YACs) harboring MHC class I genes as well as anchor genes already mapped within the human MHC complex (HLA). Five YACs containing 9 anchor genes built a contig of about 1.0-1.2 Mb between the SLA class III BAT1 locus and the olfactory receptor-like genes OLF42. Ten different SLA class I sequences, including putative allelic forms of published classical and non-classical SLA class I genes, were assigned to the 400-kb enclosing centromeric part of the contig. Three additional YACs comprising the OLF89 genes and two YACs containing the butyrophilin gene were located telomeric to the contig. Comparison between the human and porcine MHC complexes showed a perfect conserved order of anchor genes, whereas no orthologous relationships were found for the class I loci.