SEQUENCE AND PCR-RFLP ANALYSIS OF 14 NOVEL BOLA-DRB3 ALLELES

The genetic diversity of the bovine class II DRB3 locus was investigat ed by polymerase chain reaction (PCR) amplification and DNA sequencing of the first domain exon. Studying 34 animals of Various cattle breed s, 14 previously unrecognized DRB3 alleles were identified. In three a lleles, amino acid substitutions were observed that had not been previ ously found in bovine DRB3, but occurred at the same position in bovin e DQB and in the DRB alleles of other mammals. For all newly identifie d alleles, the restriction fragment length polymorphism (RFLP) pattern s of PCR products obtained with the enzymes RsaI, BstYI, and HaeIII we re compared with patterns of 38 previously described alleles. Altogeth er, eleven novel PCR-RFLP types were defined. Twelve out of the 42 PCR -RFLP types identified so far were not found to be fully informative b ecause they corresponded to more than one allelic sequence. PCR-RFLP m ay therefore be a rapid and useful method for DRB3 typing in cattle fa milies, but for studies on outbred populations, sequencing and hybridi zation techniques are required.