大肠杆菌是引起奶牛乳腺炎发生的常见病因。嗜中性粒细胞（PMN）是炎症反应的第一效应者。研究表明PMN的DNA甲基化调控在人类疾病易感性中发挥关键作用。健康和乳腺炎牛PMN中DNA甲基化模式存在怎样的差异，它们是否影响乳腺炎感染过程中相关基因的表达，调控机制如何？鉴于此，本课题对健康和大肠杆菌乳腺炎半同胞牛血液PMN进行RNA-seq和简化甲基化测序；整合转录组和甲基化数据，筛选与炎症/免疫相关的基因；通过亚硫酸盐测序和实时荧光定量PCR验证基因甲基化水平和表达，鉴定调控基因表达的甲基化位点；构建乳腺上皮细胞和嗜中性粒细胞炎症模型，研究关键基因的甲基化调控机制；分析目标基因关键甲基化位点的群体效应，以期挖掘出与奶牛乳腺炎症反应相关的表观遗传学标记，揭示DNA甲基化在乳腺炎感染过程中发挥作用的分子基础，为奶牛乳腺炎的育种和治疗提供新的靶点。

Escherichia coli are the common cause of leading to bovine mastitis. Neutrophils (PMN) are the first effectors of the inflammatory response. Recent studies have shown that PMN DNA methylation plays a key role in the regulation of human disease susceptibility. Our questions are whether the DNA methylation patterns of bovine PMN are differences between in the healthy cows and mastitis cows, whether the variation in DNA methylation patterns affect the infection process of cow mastitis, what is the regulatory mechanism? Based on the above questions, in the present study, firstly we are going to sequenced the blood neutrophils of healthy and Escherichia coli infected mastitis half-sib cows using the RNA-seq and Reduced Representation Bisulfite Sequencing methods; we do the joint analysis of transcriptome and methylation data, select the target genes associated with immune and inflammation; and then by the bisulfite sequencing and Real-time PCR, we detect the methylation levels and expression levels of genes in the samples, screen the methylation sites of regulation gene expression; by the use of mammary epithelial cells and neutrophils, we build the inflammatory cells model and study the key regulatory mechanism of gene methylation; finally, we analyze the effect of target gene methylation sites in population level. We would excavate the epigenetic markers associated with cow mastitis inflammation basing on the genome-wide DNA methylation dataset. The findings would provide insights into the molecular mechanism of DNA methylation in mastitis infection process and new targets for breeding and treatment of mastitis.