Division of Animal Infectious Disease, State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China.
Arch Microbiol. 2012 Mar;194(3):167-76. doi: 10.1007/s00203-011-0741-6. Epub 2011 Aug 17.
Actinobacillus pleuropneumoniae, one of the most important porcine respiratory pathogens, exhibits tight adherence to cell surfaces. The Flp pilus, which is assembled by the proteins encoded by the flp (fimbrial low-molecular-weight protein) operon, may play an important role in the bacterial adherence. In this study, the flp operons of twelve A. pleuropneumoniae serotype reference strains were sequenced and analyzed. The phenotypic diversity of fimbriae was observed using transmission electron microscopy, and the adherence ability was tested against a porcine lung epithelial cell line. The complete flp operon was identified in the reference strains of serotypes 1, 4, 5, 7, 12, and 13, consisting of 14 genes (flp1-flp2-tadV-rcpCAB-tadZABCDEFG). Fimbriae were observed protruding from the bacterial cell surfaces of these strains. In contrast, the flp promoter was absent in serotypes 2, 3, 6, 9, and 11, and the flp1 gene was truncated in serotypes 10 and 15. No pilus was observed on the surfaces of these strains. The piliated strains have higher efficiency of adhesion than the pilus-negative strains. Our data demonstrated that the Flp pili are involved in A. pleuropneumoniae adherence. The genetic diversity of the flp operons among different strains may contribute, at least in part, to the variation in virulence of Actinobacillus pleuropneumoniae.
副猪嗜血杆菌是最重要的猪呼吸道病原体之一，它能紧密黏附于细胞表面。Flp 菌毛由 flp（纤毛低分子量蛋白）操纵子编码的蛋白组装而成，可能在细菌黏附中发挥重要作用。在本研究中，对 12 株副猪嗜血杆菌血清型参考菌株的 flp 操纵子进行了测序和分析。使用透射电子显微镜观察菌毛的表型多样性，并测试了对猪肺上皮细胞系的黏附能力。在血清型 1、4、5、7、12 和 13 的参考菌株中鉴定出完整的 flp 操纵子，由 14 个基因（flp1-flp2-tadV-rcpCAB-tadZABCDEFG）组成。这些菌株的细菌表面观察到菌毛突出。相比之下，血清型 2、3、6、9 和 11 中缺失 flp 启动子，血清型 10 和 15 中 flp1 基因缺失。这些菌株表面未观察到菌毛。有菌毛的菌株比无菌毛的菌株黏附效率更高。我们的数据表明，Flp 菌毛参与了副猪嗜血杆菌的黏附。flp 操纵子在不同菌株中的遗传多样性至少部分导致了副猪嗜血杆菌毒力的变异。
