已有21个国家和地区报道左氏无绿藻导致奶牛发生乳房炎，具有爆发性和高致病性，属于人畜共患病。其发病率和传播率正在逐渐增高和扩大，已经引起业界的广泛关注。本课题组已经在我国北京、天津和山东奶牛乳房炎的乳汁中分离鉴定出左氏无绿藻。但是它对奶牛乳腺上皮细胞侵染凋亡的机制还不清楚。本研究旨在通过我们分离的左氏无绿藻体外感染奶牛乳腺上皮细胞，利用透射电镜观察左氏无绿藻对奶牛乳腺上皮细胞的侵染，Hoechst33258染色法检测上皮细胞的凋亡过程，分析左氏无绿藻介导奶牛乳腺上皮细胞凋亡时死亡受体Fas，线粒体凋亡酶激活因子Caspases，MAPK通路中p53、bcl-2、bax、p300/CBP和ROS，炎性细胞因子IL-1、IL-6、IL-12、TNF、IFN，模式识别受体TLR2和TLR4及其NF-κB信号传递途径的变化，以此阐明左氏无绿藻对奶牛乳腺上皮细胞侵染凋亡的机制。

Bovine mastitis cases caused by Prototheca zopfii have been reported in 21 countries all over the world, which were considered to be pathogenic and refractory. The morbidity of this diesease is becoming popular and has been focused by researchers and veterinarian for bovine mastitis. Currently, Prototheca zopfii strains firstly isolated from Chinese milk samples of cows suffering from mastitis through Beijing, Tianjing and Shandong dairy farms by our group and the results have been published on SCI journals. However, the mechanism of this kind of mastitis has not been elucidated, particularly, the molecular characteristics of epithelial cell line from bovine mammary gland adhering, invading and apoptosis by Prototheca zopfii are not clear until now. The objective of this program is therefore, to observe Prototheca zopfii adhered BMEC by scanning electronic microscopy and transmission electronic microscopy, and apoptosis of BMEC by hoechst33258 staining, to analyze Prototheca zopfii adhered and invaded BMEC cytokines Fas, caspases, p53, bcl-2、bax、p300/CBP and ROS by qPCR, western blot and flow cytometry, to study the effect of Prototheca zopfii adhered and invaded BMEC cytokines included IL-1、IL-6、IL-12、TNF、IFN, and immune responses TLR2 and TLR4 by Real-time PCR, western blot and ELISA. The program finally demonstrated the molecular characteristics of epithelial cell line from bovine mammary gland adhering, invading and apoptosis by Prototheca zopfii.