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1 September 2008 Iron Acquisition by Ornithobacterium rhinotracheale
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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 µM 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 µM and 100 µM, 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.

Adquisición de hierro por parte del Ornithobacterium rhinotracheale.

El Ornithobacterium rhinotracheale es un patógeno respiratorio emergente en las aves domésticas de Norte América que está causando millones de dólares en pérdidas a la industria avícola. El Ornithobacterium rhinotracheale se asocia con aerosaculitis, pleuritis, neumonía y consolidación en los pulmones. Poco se conoce sobre los mecanismos moleculares de infección. En este estudio se exploraron los mecanismos de adquisición de hierro por parte del Ornithobacterium rhinotracheale. Según se determinó mediante pruebas de agar de cromo azurol-S y de solución de cromo azurol-S, las cepas de Ornithobacterium rhinotracheale cultivadas con deprivación de hierro en un medio con 200 µm de 2,2′-dipiridil, no secretaron sideróforos. Discos impregnados con diferentes compuestos protéicos unidos a hierro y sales inorgánicas de hierro Fe (III) y Fe (II) colocadas en agar deprivado de hierro inoculado con una capa de O. rhinotracheale, permitieron crecimiento a partir de hemoglobinas de oveja y cerdo, de ovotransferrinas, Fe (III) y Fe (II), pero no a partir de transferrina bovina, apo-transferrina bovina, lactotransferrina bovina y hemina, Fe (III) y Fe (II). Sin embargo, tanto la hemoglobina como la transferrina bovina permitieron el crecimiento del O. rhinotracheale tipo C. En extractos de membrana de O. rhinotracheale, se detectaron cuatro proteínas inmunoreactivas relacionadas con el proceso de adquisición de hierro mediante espectrofotometría de masa. Además, las cepas de campo de O. rhinotracheale mostraron diferente sensibilidad al 2,2′-dip

Louisa B. Tabatabai, Emilie S. Zehr, Mandy K. Zimmerli, and Kakambi V. Nagaraja "Iron Acquisition by Ornithobacterium rhinotracheale," Avian Diseases 52(3), 419-425, (1 September 2008).
Received: 3 December 2007; Accepted: 1 March 2008; Published: 1 September 2008

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