Wang MengYi, Zhang PengYun, Zhu DeKang, Wang MingShu, Jia RenYong, Chen Shun, Sun KunFeng, Yang Qiao, Wu Ying, Chen XiaoYue, Biville Francis, Cheng AnChun, Liu MaFeng
Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China; Research Center of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China.
Research Center of Avian Disease, College of Veterinary Medicine of Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan 611130, PR China.
Vet Microbiol. 2017 Mar;201:162-169. doi: 10.1016/j.vetmic.2017.01.027. Epub 2017 Jan 24.
Riemerella anatipestifer is an important bacterial pathogen in ducks and causes heavy economic losses in the duck industry. However, the pathogensis of this bacterium is poorly understood. In this study, a putative outer membrane hemin receptor gene B739_1208 in R. anatipestifer CH-1 was deleted to determine the relationship between iron uptake and virulence. The R. anatipestifer CH-1ΔB739_1208 mutants grew significantly more slowly than the wild-type bacteria in TSB liquid medium. Further characterization revealed that the R. anatipestifer CH-1ΔB739_1208 mutants were deficient in iron uptake. Animal experiments indicated that the median lethal dose of the wild-type RA-CH-1 in ducklings was 3.89×10, whereas the median lethal dose of the R. anatipestifer CH-1ΔB739_1208 mutant in ducklings was 5.68×10. The median lethal dose of the complementation strain in ducklings was 9.84×10. Additional analysis indicated that bacterial loads in the blood, liver, and brain tissues in the R. anatipestifer CH-1ΔB739_1208-infected ducklings were significantly decreased compared to those in the wild-type R. anatipestifer CH-1 infected ducklings. In a duck co-infection model with R. anatipestifer CH-1 and R. anatipestifer CH-1ΔB739_1208, the R. anatipestifer CH-1B739_1208 mutant was outcompeted by the wild-type R. anatipestifer CH-1 in the blood (P<0.002), livers (P<0.001) and brains (P<0.001) of infected ducks, indicating that B739_1208 gene expression provided a competitive advantage in these organs. Our results demonstrate that the B739_1208 gene is a virulence factor in R. anatipestifer CH-1.
鸭疫里默氏菌是鸭体内一种重要的细菌病原体，给养鸭业造成了巨大的经济损失。然而，人们对这种细菌的致病机制了解甚少。在本研究中，鸭疫里默氏菌CH-1中一个假定的外膜血红素受体基因B739_1208被删除，以确定铁摄取与毒力之间的关系。鸭疫里默氏菌CH-1ΔB739_1208突变体在TSB液体培养基中的生长速度明显比野生型细菌慢。进一步的特征分析表明，鸭疫里默氏菌CH-1ΔB739_1208突变体在铁摄取方面存在缺陷。动物实验表明，野生型RA-CH-1在雏鸭中的半数致死剂量为3.89×10，而鸭疫里默氏菌CH-1ΔB739_1208突变体在雏鸭中的半数致死剂量为5.68×10。互补菌株在雏鸭中的半数致死剂量为9.84×10。额外的分析表明，与野生型鸭疫里默氏菌CH-1感染的雏鸭相比，鸭疫里默氏菌CH-1ΔB739_1208感染的雏鸭血液、肝脏和脑组织中的细菌载量显著降低。在鸭疫里默氏菌CH-1和鸭疫里默氏菌CH-1ΔB739_1208的共感染模型中，鸭疫里默氏菌CH-1B739_1208突变体在感染鸭的血液（P<0.002）、肝脏（P<0.001）和大脑（P<0.001）中被野生型鸭疫里默氏菌CH-1竞争淘汰，这表明B739_1208基因的表达在这些器官中提供了竞争优势。我们的结果表明，B739_1208基因是鸭疫里默氏菌CH-1中的一个毒力因子。
