Short communication: characterization of DRB3 alleles in the MHC of Japanese shorthorn cattle by polymerase chain reaction-sequence-based typing.

A study was made of exon 2 of the bovine leukocyte antigen BoLA-DRB3 gene of 176 Japanese Shorthorn cattle at six farms in Japan using polymerase chain reaction-sequence-based typing (PCR-SBT). An initial round of PCR using conserved locus-specific primers, a second round of PCR using a locus-specific primer, and at least one sequence-specific primer (SSP), followed by direct sequencing of products of PCR with SSP were conducted. Twenty-one BoLA-DRB3 alleles were identified with frequencies ranging from 0.3 to 19.6% in 176 individuals, and two of these alleles were new alleles that have not been reported previously. The three most frequently observed alleles (DRB3*1201, *0301, and *0801) accounted for 43.8% of the alleles in the population of these herds. Next, we tested the products of amplification by PCR of BoLA-DRB3 exon 2 with RsaI, BstYI, and HaeIII, and identified 18 previously described PCR-restriction fragment length polymorphism (RFLP) types. The PCR-RFLP types reflected the results of PCR-SBT exactly. Our results indicate that exon 2 of the BoLA-DRB3 gene is highly polymorphic in Japanese Shorthorn cattle.