Identification of novel molecular markers of mastitis caused by Staphylococcus aureus using gene expression profiling in two consecutive generations of Chinese Holstein dairy cattle

BackgroundMastitis in dairy cows caused byStaphylococcus aureusis a major problem hindering economic growth in dairy farms worldwide. It is difficult to prevent or eliminate due to its asymptomatic nature and long persistence of infection. Although transcriptomic responses of bovine mammary gland cells to pathogens that cause mastitis have been studied, the common responses of peripheral blood leukocytes toS. aureusinfection across two consecutive generations of dairy cattle have not been investigated.MethodsIn the current study, RNA-Seq was used to profile the transcriptomes of peripheral blood leukocytes sampled fromS. aureus-infected mothers and theirS. aureus-infected daughters, and also healthy non-infected mothers and their healthy daughters. Differential gene expression was evaluated as follows: 1)S. aureus-infected cows versus healthy non-infected cows (S vs. H, which include all the mothers and daughters), 2)S. aureus-infected mothers versus healthy non-infected mothers (SM vs. HM), and 3)S. aureus-infected daughters versus healthy non-infected daughters (SMD vs. HMD).ResultsAnalysis of all identified expressed genes in the four groups (SM, SMD, HM, and HMD) showed thatEPOR,IL9,IFNL3,CCL26,IL26were exclusively expressed in both the HM and HMD groups, and that they were significantly (P Padj. 1.2) were detected in the three comparisons, respectively. DEGs withP 2 were used for functional enrichment analyses. For the S vs. H comparison, DEGs detected includedCCL20,IL13andMMP3, which are associated with the IL-17 signaling pathway. In the SM vs. HM and SMD vs. HMD comparisons, five (BLA-DQB,C1R,C2,FCGR1A, andKRT10) and six (BLA-DQB,C3AR1,CFI,FCAR,FCGR3A, andLOC10498484) genes, respectively, were involved in theS. aureusinfection pathway.ConclusionsOur study provides insights into the transcriptomic responses of bovine peripheral blood leukocytes across two generations of cattle naturally infected withS. aureus. The genes highlighted in this study could serve as expression biomarkers for mastitis and may also contain sequence variation that can be used for genetic improvement of dairy cattle for resilience to mastitis.