The association of the polymorphism of bovine leukocyte
antigen (BoLA-DRB3) genes identified by the polymerase chain reaction sequence-based typing (PCR-SBT) method with resistance and susceptibility to
mastitis caused by pathogenic bacteria was investigated. Blood samples for
DNA extraction were collected from 194 Holstein cows (41 healthy cows and 153
mastitis cows including 24
mixed-infection cows infected with 2 or 3 species of pathogens) from 5 districts of Chiba prefecture, Japan. Sixteen
BoLA-DRB3 alleles were detected. The 4 main alleles of DRB3*0101, *1501, *1201, and *1101 constituted 56.8% of the total number of alleles detected.
Mastitis cows were divided into 2 groups: group 1 with single-
infection cows and group 2 with all
mastitis cows including 24
mixed-infection cows. The differences in the frequencies of
BoLA-DRB3 alleles and the number of cows homozygous or heterozygous for each
BoLA-DRB3 allele between healthy cows and the 2 groups of
mastitis cows were evaluated. Furthermore, similar comparisons were performed between healthy cows and the 2 groups of
mastitis cows for each
mastitis pathogen. It was considered that the 4 alleles, namely, DRB3*0101, *1501, *1201, and *1101 had specific resistance and susceptibility to 4 different
mastitis pathogens. Thus, DRB3*0101 might be associated with susceptibility to
coagulase-negative Staphylococci and Escherichia coli, and DRB3*1501 might be associated with susceptibility to Escherichia coli. However, DRB3*1101 might be associated with resistance to Streptococci and
coagulase-negative Staphylococci, and DRB3*1201, with resistance to Streptococci, Escherichia coli, and Staphylococcus aureus.