Wang Yi-Ping, Hsieh Ming-Kun, Tan Duen-Huey, Shien Jui-Hung, Ou Shan-Chia, Chen Chih-Feng, Chang Poa-Chun
Graduate Institute of Microbiology and Public Health, National Chung Hsing University, Taichung 402, Taiwan.
Department of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan.
Vet Microbiol. 2014 Dec 5;174(3-4):474-482. doi: 10.1016/j.vetmic.2014.10.013. Epub 2014 Oct 25.
The haemagglutinin (HA) protein plays a key role in the immunogenicity and pathogenicity of Avibacterium paragallinarum. A 210-kDa protein (HMTp210) was previously reported to be the HA of Av. paragallinarum, but the biological function of HMTp210 is not well defined. In this study, mutant strains that lacked HMTp210 were constructed using the TargeTron(®) gene knockout system. Haemagglutination and haemagglutination-inhibition (HI) assays showed that the HMTp210-deficient mutants exhibited no HA activity and failed to elicit HI antibodies in immunized chickens. Additionally, HMTp210-deficient mutants exhibited reduced ability to adhere to HeLa cells and to form biofilms on abiotic surfaces. Virulence assays showed that HMTp210-deficient mutants are less virulent than their isogenic wild-type strains. HMTp210 bears significant similarity to proteins of the trimeric autotransporter adhesin (TAA) family, and recombinant HMTp210 expressed in E. coli formed a trimeric structure. Taken together, these results indicated that HMTp210 is a trimeric autotransporter adhesin that confers haemagglutination, cell adherence and biofilm formation activities. These results should prove valuable to further elucidate the biological function of HA and the mechanism of pathogenicity of Av. paragallinarum.
血凝素（HA）蛋白在副鸡禽杆菌的免疫原性和致病性中起关键作用。先前报道一种210 kDa的蛋白（HMTp210）是副鸡禽杆菌的HA，但HMTp210的生物学功能尚未明确界定。在本研究中，使用TargeTron®基因敲除系统构建了缺乏HMTp210的突变菌株。血凝和血凝抑制（HI）试验表明，缺乏HMTp210的突变体没有HA活性，并且在免疫鸡中未能引发HI抗体。此外，缺乏HMTp210的突变体在粘附HeLa细胞和在非生物表面形成生物膜方面的能力降低。毒力试验表明，缺乏HMTp210的突变体的毒力低于其同基因野生型菌株。HMTp210与三聚体自转运粘附素（TAA）家族的蛋白具有显著相似性，并且在大肠杆菌中表达的重组HMTp210形成三聚体结构。综上所述，这些结果表明HMTp210是一种三聚体自转运粘附素，赋予血凝、细胞粘附和生物膜形成活性。这些结果对于进一步阐明HA的生物学功能和副鸡禽杆菌的致病机制应具有重要价值。
