Role of long polar fimbriae type 1 and 2 in pathogenesis of mammary pathogenic Escherichia coli

文献类型： 外文期刊

第一作者： Zhou, Mingxu

作者： Zhou, Mingxu;Ma, Fang;Xu, Yue;Deng, Bihua;Zhang, Jinqiu;Lu, Yu;Yang, Yang;Zhu, Guoqiang;Yang, Yang;Zhu, Guoqiang;Wu, Miaomiao;Zhou, Mingxu;Zhu, Guoqiang;Lu, Yu

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关键词： long polar fimbriae; mastitis; Escherichia coli; pathogenesis; inflammatory response

期刊名称：JOURNAL OF DAIRY SCIENCE （ 影响因子：4.034； 五年影响因子：4.354 ）

ISSN： 0022-0302

年卷期： 2021 年 104 卷 7 期

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收录情况： SCI

摘要： Escherichia coli is a leading cause of bovine mastitis worldwide. The bacteria can rapidly grow in milk and elicit a strong lipopolysaccharide (LPS)/toll-like receptor-4 (TLR4)-dependent inflammatory response. Recently, the long polar fimbriae (LPF) were identified as a promising virulence factor candidate widely distributed in mammary pathogenic E. coli (MPEC) strains. Mammary pathogenic E. coli possess 2 lpf loci encoding LPF1 and LPF2, respectively. By deleting the major fimbrial subunit gene, lpfA, we found that both LPF1 and LPF2 contribute to MPEC adhesion, invasion, and biofilm formation in vitro. The lpf1A and lpf2A mutants showed reduced cytotoxicity in our in vitro cell infection model. Furthermore, we observed that LPF2 induced a mild TLR4-independent proinflammatory response. The median lethal dose (LD50) of both Delta lpf2A and Delta lpf1A Delta lpf2A mutants to BALB/c mice increased by 0.38 and 0.15 logs, respectively, whereas that of wild-type strain MPJS13 was 8.69 logs. In contrast, LPF1 deficiency significantly enhanced the LPS/TLR4-mediated inflammatory response in mammary epithelial cells, and the LD50 of the mutant decreased to 8.18 logs. In conclusion, our data suggested that LPF are important in MPEC colonization of mammary cells and may provide a benefit to bacterial intracellular survival that induces persistent bovine mastitis.

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