Tabatabai Louisa B, Zehr Emilie S, Zimmerli Mandy K, Nagaraja Kakambi V
Respiratory Diseases of Poultry, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA.
Avian Dis. 2008 Sep;52(3):419-25. doi: 10.1637/8185-113007-Reg.
Ornithobacterium rhinotracheale (ORT) is an emerging respiratory pathogen of poultry in North America that is causing millions of dollars in economic losses to the poultry industry. Ornithobacterium rhinotracheale is associated with airsacculitis, pleuritis, pneumonia, and consolidation of lungs. Little is known about the molecular mechanisms of infection. In this study, the mechanism of iron acquisition by O. rhinotracheale was explored. O. rhinotracheale strains grown under iron deprivation in media containing 200 microM 2,2'-dipyridyl did not secrete siderophores as measured by the chrome azurol S (CAS) agar and CAS solution assays. Filter disks impregnated with various protein-bound iron compounds and inorganic iron salts of Fe(III) and Fe(II) placed on iron-restricted agar inoculated with a lawn of O. rhinotracheale supported growth from sheep and porcine hemoglobins, ovotransferrin, Fe(III), and Fe(II), but they did not support growth from bovine transferrin, bovine apo-transferrin, bovine lactoferrin, and hemin. However, both bovine hemoglobin and transferrin supported growth of O. rhinotracheale serotype C. Four immunoreactive proteins involved in iron acquisition were identified in an O. rhinotracheale membrane extract by using mass spectrometry. Furthermore, O. rhinotracheale field strains showed differential sensitivity to 2,2'-dipyridyl. Of the 72 field strains tested, 22 strains were resistant to the iron chelator at concentrations of 50 microM and 100 microM, suggesting this attribute may be related to disease-producing potential of these strains. This is the first report on the identification of the iron acquisition mechanism of O. rhinotracheale.
禽气管鸟杆菌（ORT）是北美一种新出现的家禽呼吸道病原体，给家禽业造成了数百万美元的经济损失。禽气管鸟杆菌与气囊炎、胸膜炎、肺炎和肺实变有关。人们对其感染的分子机制知之甚少。在本研究中，对禽气管鸟杆菌获取铁的机制进行了探索。通过铬天青S（CAS）琼脂和CAS溶液测定法检测，在含有200微摩尔2,2'-联吡啶的培养基中缺铁条件下生长的禽气管鸟杆菌菌株不分泌铁载体。将浸有各种蛋白质结合铁化合物以及Fe(III)和Fe(II)的无机铁盐的滤纸片放置在接种有禽气管鸟杆菌菌苔的缺铁琼脂上，结果表明，来自绵羊和猪血红蛋白、卵转铁蛋白、Fe(III)和Fe(II)的铁能支持其生长，但来自牛转铁蛋白、牛脱铁转铁蛋白、牛乳铁蛋白和血红素的铁则不能。然而，牛血红蛋白和转铁蛋白都能支持禽气管鸟杆菌C血清型的生长。通过质谱分析在禽气管鸟杆菌膜提取物中鉴定出了四种参与铁获取的免疫反应性蛋白。此外，禽气管鸟杆菌田间菌株对2,2'-联吡啶表现出不同的敏感性。在测试的72株田间菌株中，有22株在50微摩尔和100微摩尔浓度下对铁螯合剂具有抗性，这表明该特性可能与这些菌株的致病潜力有关。这是关于禽气管鸟杆菌铁获取机制鉴定的首次报道。
