牛白血病病毒（BLV）在世界范围内广泛流行，可经血液和淋巴系统下行持续感染奶牛乳腺上皮细胞，导致细胞抗菌能力下降，促进乳腺炎症的发生发展。BLV编码的miRNAs（BLV-miRNAs）作为BLV致病的关键作用元件，可修饰宿主基因表达、促进BLV复制、调控病毒与宿主细胞的相互作用、并具有跨界影响人类健康的潜在风险。前期研究结果显示，BLV-miRNAs可能靶向并抑制细胞抗菌物理和化学屏障等相关基因的转录。我们推测，在乳腺上皮细胞微环境中，BLV-miRNAs可能介导细菌与病毒的协同作用促进乳腺炎症的发生发展。因此，本项目拟以BLV-miRNAs调控细菌与病毒的协同作用为切入点，综合运用多种实验技术，明确BLV-miRNAs影响奶牛乳腺上皮细胞抗菌功能的作用机制，既可以为防控奶牛乳腺炎症提供新思路，还可为切断牛奶传播病毒的风险、提高牛奶中生物活性物质含量、保障人类健康提供研究依据。

Bovine leukosis virus (BLV) is widespread in the world, which cause persistent infection in bovine mammary epithelial cells through the blood and lymphatic system, affecting their response to bacteria and favoring the development of mastitis. As functional elements required for BLV pathopoiesis, BLV-miRNAs can modify the pattern of gene expression of the host, promote BLV replication, regulate viral-host synergy, and have potential risk of cross-kingdom impact on human. In previous bioinformatics analysis, BLV-miRNAs may target and inhibit the transcription of genes which related to physical and chemical barriers of cell antibacterial. We hypothesize that, in the mammary epithelial microenvironment, BLV-miRNAs may promote bacterial–viral synergy and favoring the development of mastitis. Therefore, this project intends to start with BLV-miRNAs regulate the synergism of bacteria and virus , comprehensive multiple experimental techniques, clarify the mechanism of BLV-miRNAs in the antibacterial function of bovine mammary epithelial cells. It can provide a new method to prevent and control mastitis, and also provide research basis to cut off the risk of transmitting viruses through milk, improve the milk bioactive substances and protect the health of human.