The MHC of a broiler chicken line: serology, B-G genotypes, and B-F/B-LB sequences

Although the major histocompatibility complex of chickens (encoded in the B complex) has been studied for a number of years, almost all work has focus ed on the White Leghorn breed. Broiler (meat-type) chickens were derived fr om other breeds, including Cornish and Plymouth Rock. It was our hypothesis that new B haplotypes, not previously identified in White Leghorns, might be present in lines of broiler chickens. Furthermore, alloantisera used to identify B serotypes in Leghorn lines reportedly do not work well outside t he line in which they were raised, with the result that broiler B haplotype s have not been incorporated into the universal nomenclature system. Our ap proach was to use a panel of B alloantisera produced to identify B serotype s within a commercial broiler breeder line (designated line A). B homozygot es identified serologically were compared by B-G genotyping using restricti on fragment length polymorphism analysis. Furthermore, reverse transcriptio n-polymerase chain reaction was used to amplify variable domains of express ed B-LB and B-F genes of homozygotes of most of the B serotypes in Line A, followed by cloning and nucleotide sequence determination. Comparison of B- LB and B-F sequences with standard Leghorn haplotypes demonstrated the exis tence of new alleles of B-L and B-F in a broiler breeder line, as well as t he presence of alleles previously identified in Leghorns. In some cases, Le ghorn-type alleles were in linkage with different B-G alleles in the broile r line than the common haplotypic associations found in Leghorn lines.