Submitted to: North Central Avian Disease Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/15/2008
Publication Date: 3/14/2008
Citation: Tabatabai, L.B., Zehr, E.S., Zimmerli, M.K., Nagaraja, K.V. 2008. Iron acquisition by Ornithobacterium rhinotracheale [abstract]. North Central Avian Disease Conference, March 16-18, 2008, St. Paul, Minnesota. p. 25. Interpretive Summary:
Technical Abstract: Ornithobacterium rhinotracheale (ORT) is an emerging respiratory pathogen of poultry in North America that causes sporadic outbreaks of airsacculitis in poultry, and is associated with, pleuritis, consolidation of lungs and pneumonia. Little is known about the virulence mechanisms of this organism. In this study we explore the mechanism of iron acquisition by ORT by simulating low iron growth conditions by incorporating an iron chelator into the growth medium. Pathogens may respond to restricted iron conditions by secreting siderophores and/or upregulating outer membrane-associated receptors and iron transport proteins. When ORT is grown under iron-restricted conditions in brain heart infusion broth containing 200 µM 2,2’-dipyridyl, no siderophores were detected in the growth medium. Iron sources that supported growth included Fe(III) and Fe (II), bovine, sheep and porcine hemoglobins and ovotransferrin. Bovine transferrin, bovine apo-transferrin, bovine lactoferrin, and hemin did not support growth of ORT. Proteins involved in iron acquisition were identified from a 2-D gel of an outer membrane preparation and included Haemophilus influenzae homologs heme-hemopexin, hxuB (Accession No. P45356), and an iron transport protein (Accession No. Q57449). Furthermore, seventy two field strains of ORT obtained from various turkey flocks were tested for their sensitivity to the iron chelator, 2,2’-dipyridyl, in a microtiter plate assay. Results showed that 22 of 72 strains tested were resistant to the iron chelator at concentrations of 50 and 100 µM, suggesting the presence of an inducible iron acquisition mechanism. The information obtained in this study allows us to design strategies for the control of O. rhinotracheale infection of poultry.