Abstract:

Dairy mastitis, a common and complex disease with a high incidence, takes its toll on the development of world dairy industry, brings economic losses of billions of dollars per year. Clinical and subclinical mastitis, caused by pathogens such as Staphylococcus aureus, Escherichia coli and Streptococcus agalactiae, posed a huge security risk to milk industry. In recent years, with the continuous breakthrough of sequencing technology and decline of sequencing cost, the research of life science has entered into the Omics era. The traditional methods such as histopathological screening, somatic cell counting, milk PH value detection, detection of milk conductivity, enzyme activity test, infrared thermal imaging can be employed for clinical diagnosis of dairy cow mastitis, but these methods are not powerful enough to elucidate the pathogenesis in a cellular or molecular view. Omics technologies are mainly composed of genomics, proteomics and metabolomics. Genomics can not only reveal the phenotypic variation and genetic basis of the complex trait of dairy mastitis at the transcriptional level, but also reveal the molecular patterns of the mastitis from the aspects of transcriptional regulation (miRNAs, LncRNAs, etc.) and epigenetic modification (DNA methylation, histone modification, etc.). Genomic analysis of mastitis can also dig out the related changes of DNA, RNA and the rules of multi-molecule interaction, which accounts for a better understanding of the immune mechanism of the host against the pathogen, so as to screen and identify the signal pathways and key candidate genes of mastitis resistance, thus improving the accuracy of genome prediction or selection. Proteomics can not only compare milk protein type and abundance but also analyze protein interaction and post-translational modification in breast tissues under different states and environments. The differentially expressed proteins are annotated by COG (Cluster of Orthologous Groups of protein) function followed by database comparison, GO and Pathway enrichment analysis, which help bring to light the complex regulatory mechanism of mastitis occurrence and defense process at protein level. Proteomic analysis can also be used to find molecular marker of mastitis diagnosis, which will provide a potential precise target for the development of therapeutic drugs. Metabolomics, an important part of the system biology, can detect metabolites of low molecular weight (such as amino acids, lipids, carbohydrates, etc.) of the specific tissues or organs in specific environment or specific physiological states. Efficient qualitative and quantitative analysis will elucidate the relevant metabolic pathways. As the ultimate downstream of gene expression, metabolomics technology enables small changes in gene expression and protein synthesis to be amplified at metabolite levels to fully reflect cellular functions, whose application in dairy mastitis will be able to identify related biomarkers and reveal the physiological and pathological changes of dairy breasts. In conclusion, applying Omics or multi-Omics association analysis techniques to mastitis can further reveal the pathogenic defense mechanism, which will provide valuable reference for disease prediction, diagnosis and treatment. This paper reviews the latest research progress about application of Omics in the field of cow mastitis, aiming to provide solid theoretical bases and practical references for cow health and safety of dairy industry in China.

Key words: Omics, cow, mastitis