A PCR method for typing B-L beta II family (class II MHC) alleles in broiler chickens

Certain haplotypes of the major histocompatibility (B) complex are strongly associated with resistance or susceptibility to several infectious disease s in Leghorn chickens. Identification of chicken haplotypes based on the nu cleotide sequence of B complex loci could provide more precise identificati on of haplotypes than traditional serological methods, We report the develo pment and application of polymerase chain reaction with sequence specific p rimers (PCR-SSP) to type broiler chicken B haplotypes based on the DNA sequ ence of B-L beta II family genes. Five well-defined standard B haplotypes f rom White Leghorns and 12 recently characterized B haplotypes from a broile r breeder line were used to develop the test system. The B-L beta II family loci were amplified from genomic DNA by B-L beta II family specific primer s and then characterized by PCR-SSP. In total, ten pairs of primers, derive d from the sequences of expressed B-L beta II family alleles, were used in the PCR typing test to discriminate the chicken B haplotypes identified pre viously by serological means. The PCR-SSP showed that each haplotype had a different amplification pattern, except those haplotypes known or suspected to have the same B-L beta alleles. Cloning and sequencing of the family sp ecific PCR products indicated that two loci in the B-L beta II family, pres umably B-L beta I and B-L beta II, were amplified. Finally, B-L beta PCR-SS P typing was used in combination with B-G RFLP analyses to characterize unu sual (variant) B serotypes; the results indicate that some of these are nat ural recombinants within the B complex.