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Iron acquisition by Ornithobacterium rhinotracheale
Louisa B Tabatabai1, Emilie S Zehr, Mandy K Zimmerli
1Respiratory Diseases of Poultry, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA. louisa.tabatabai@ars.usda.gov
Avian Diseases
|October 23, 2008
Summary
Ornithobacterium rhinotracheale (ORT) does not produce siderophores but can acquire iron from hemoglobin and transferrin. Some ORT strains exhibit resistance to iron chelators, potentially linked to virulence.
Area of Science:
- Veterinary Microbiology
- Poultry Pathology
- Bacterial Pathogenesis
Background:
- Ornithobacterium rhinotracheale (ORT) is a significant poultry pathogen causing economic losses.
- ORT infections lead to respiratory diseases like airsacculitis and pneumonia.
- The molecular mechanisms of ORT infection, particularly iron acquisition, are poorly understood.
Purpose of the Study:
- To investigate the iron acquisition mechanisms of Ornithobacterium rhinotracheale.
- To identify potential virulence factors related to iron uptake in ORT.
Main Methods:
- Culturing ORT under iron-restricted conditions with 2,2'-dipyridyl.
- Assessing siderophore production using CAS agar and solution assays.
- Evaluating bacterial growth on iron-restricted media supplemented with various iron sources.
- Identifying iron acquisition proteins via mass spectrometry.
- Testing field isolates for sensitivity to 2,2'-dipyridyl.
Main Results:
- ORT did not secrete siderophores under iron-limited conditions.
- ORT could utilize sheep/porcine hemoglobin, ovotransferrin, Fe(III), and Fe(II) for growth.
- Bovine hemoglobin and transferrin supported growth of ORT serotype C.
- Four immunoreactive iron acquisition proteins were identified in ORT membrane extracts.
- 22 out of 72 field strains showed resistance to 2,2'-dipyridyl.
Conclusions:
- Ornithobacterium rhinotracheale employs alternative iron acquisition strategies, not relying on siderophores.
- The ability to utilize specific iron sources and resistance to chelators may correlate with ORT's pathogenicity.
