Parity-dependent association between IL-12Rβ2 and IL-23R gene polymorphisms and clinical mastitis in Chinese Holstein cows

Interleukin-12 (IL-12) and interleukin-23 (IL-23) are proinflammatory cytokines produced by macrophages and dendritic cells in response to infection with intracellular pathogens. Given the importance of IL-12 and IL-23 for modulating inflammation and the host immune response, the IL-12 and IL-23 receptor genes may be suitable candidate genes for studying disease resistance in dairy cattle. DNA samples of twenty Chinese Holstein cows were selected randomly for PCR amplification and sequencing, and used for SNP discovery in the bovine IL-12Rβ2 and IL-23R promoter regions. One SNP (c.-246G>T, rs385343195) in IL-12Rβ2 and 2 SNPs [c.-856A>G (rs109216732) and c.-207T>C (rs109571825)] in IL23R were identified. Identified SNPs were genotyped in 866 Chinese Holstein cows and associations between SNPs or haplotypes and clinical mastitis infection were analyzed by logistic regression model. Significant associations between rs385343195 (IL-12Rβ2 gene) and haplotypes of SNPs rs385343195-rs109216732-rs109571825 (TGC and TAT), and clinical mastitis infection were detected depending on parity, and this provides insight into the complex mechanisms of immunity to infections. Further investigations are required to reveal the mechanisms of IL-12Rβ2 and IL-23R in mastitis susceptibility in cattle.