Conserved MHC Gene Orthologs Genetically Map to the Turkey MHC-B

The avian MHC-associated gene set includes orthologs to genes found throughout the human major histocompatibility complex (MHC), including some loci of the evolutionarily conserved class III region. In the turkey and other Galliformes, genes linked to the MHC have been identified because they are closely associated with class I or class II genes. This study was designed to evaluate additional class III genes for linkage to the avian MHC to further determine conservation of these loci in birds. BLAST searches were used to locate sequences in the turkey genome with similarity to genes shared between the MHC of Xenopus and humans. Primers were designed to target 25 genes, and putative orthologs were amplified by PCR and sequenced. Sequence polymorphisms were identified for 15 genes in turkey reference mapping families, and 8 genes showed significant genetic linkage to the turkey MHC-B locus. These new genetic markers and linkage relationships broaden our understanding of the composition of the avian MHC and expand the gene content for the turkey MHC-B.