Are cattle immune-system genes linked to resistance to mastitis progression?

Details

Mastitis is an inflammatory response of the mammary gland to irritation, injury, or infectious agents and is a major problem in the dairy industry.

Researchers used polymerase chain reaction-sequence-based typing to genotype the bovine major histocompatibility complex (BoLA)-DRB3 and BoLA-DQA1 genes in 120 Holstein cattle with clinical mastitis and 85 randomly selected Holstein cattle in Japan. They divided the cattle with mastitis into four groups according to the bacteria that caused it: Staphylococcus aureus, Streptococci, Escherichia, and coagulase-negative staphylococci.

They compared heterozygosity of BoLA-DRB3 and BoLA-DQA1 in each mastitis group with that in the control cattle. For each group and gene locus, they also compared observed heterozygosity with the heterozygosity expected under Hardy-Weinberg proportions.

For BoLA-DQA1, the Escherichia-induced and Streptococci-induced mastitis groups showed significant differences between expected and observed heterozygosity. No such differences were observed in any group for BoLA-DRB3.

Two BoLA-DQA1 alleles, BoLA-DQA1*0101 and BoLA-DQA1*10012, were associated with susceptibility to Streptococci-induced mastitis. The homozygous genotypes BoLA-DQA1*0101/0101 and BoLA-DQA1*10011/10011 were associated with susceptibility to mastitis caused by Streptococci and Escherichia, respectively. The authors described this as the first report associating BoLA-DQA1 heterozygosity with resistance to mastitis progression.