Blum Shlomo E, Heller Elimelech D, Jacoby Shamay, Krifucks Oleg, Leitner Gabriel
National Mastitis Reference Center,Kimron Veterinary Institute,Ministry of Agriculture and Rural Development,P.O. Box 6,Bet Dagan 50250,Israel.
Department of Animal Sciences,Robert H. Smith Faculty of Agriculture,Food and Environment,The Hebrew University of Jerusalem,POB 12,Rehovot 76100,Israel.
J Dairy Res. 2017 May;84(2):190-197. doi: 10.1017/S0022029917000206.
We studied the mammary immune response to different mammary pathogenic Escherichia coli (MPEC) strains in cows, hypothesising that the dynamics of response would differ. E. coli is a major aetiologic agent of acute clinical bovine mastitis of various degrees of severity with specific strains being associated with persistent infections. We compared challenge with three distinct pathogenic MPEC strains (VL2874, VL2732 and P4), isolated from different forms of mastitis (per-acute, persistent and acute, respectively). A secondary objective was to verify the lack of mammary pathogenicity of an environmental isolate (K71) that is used for comparison against MPEC in genomic and phenotypic studies. Twelve cows were challenged by intra-mammary infusion with one of the strains. Cellular and chemokine responses and bacterial culture follow-up were performed for 35 d. All cows challenged by any of the MPEC strains developed clinical mastitis. Differences were found in the intensity and duration of response, in somatic cell count, secreted cytokines (TNF-α, IL-6 and IL-17) and levels of milk leucocyte membrane Toll-like receptor 4 (TLR4). A sharp decrease of TLR4 on leucocytes was observed concomitantly to peak bacterial counts in milk. Intra-mammary infusion of strain K71 did not elicit inflammation and bacteria were not recovered from milk. Results suggest some differences in the mammary immune response to distinct MPEC strains that could be correlated to their previously observed pathogenic traits. This is also the first report of an E. coli strain that is non-pathogenic to the bovine mammary gland.
我们研究了奶牛对不同乳腺致病性大肠杆菌（MPEC）菌株的乳腺免疫反应，推测反应动态会有所不同。大肠杆菌是不同严重程度急性临床牛乳腺炎的主要病原体，特定菌株与持续性感染有关。我们比较了用三种不同的致病性MPEC菌株（VL2874、VL2732和P4）进行攻毒的情况，这些菌株分别从不同形式的乳腺炎（分别为超急性、持续性和急性）中分离得到。第二个目标是验证一种环境分离株（K71）在乳腺中的无致病性，该分离株在基因组和表型研究中用于与MPEC进行比较。12头奶牛通过乳腺内注射其中一种菌株进行攻毒。进行了35天的细胞和趋化因子反应以及细菌培养跟踪。所有受到任何一种MPEC菌株攻毒的奶牛都发生了临床乳腺炎。在反应强度和持续时间、体细胞计数、分泌的细胞因子（TNF-α、IL-6和IL-17）以及牛奶白细胞膜Toll样受体4（TLR4）水平方面发现了差异。在牛奶中细菌计数达到峰值时，观察到白细胞上的TLR4急剧下降。乳腺内注射K71菌株未引发炎症，且牛奶中未检测到细菌。结果表明，对不同MPEC菌株的乳腺免疫反应存在一些差异，这可能与其先前观察到的致病特性相关。这也是关于一种对牛乳腺无致病性的大肠杆菌菌株的首次报道。
