Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/4/1999
Publication Date: N/A
Technical Abstract: Pasteurella haemolytica A1 is a gram-negative bacterium and a bacterial pathogen that causes bovine respiratory disease (BRD) also known as shipping fever. It has been reported that an organism's ability to acquire iron in vivo may be an important virulence attribute. Pathogenic bacteria have developed one or more systems to acquire iron from a hostile environment. The pathogen can do this via production of siderophores or via the direct binding of transferrin, hemoglobin, or lactoferrin. A transferrin receptor has been recently identified for P. haemolytica, but hemoglobin and lactoferrin receptors have not been identified. The objectives of this study were to (1) identify receptors for hemoglobin, lactoferrin and transferrin expressed by P. haemolytica A1 grown under iron limitation, (2) confirm the absence of siderophore production, and (3) determine the effect of divalent metal ions on the expression of FbpA. The eresults showed that P. haemolytica did not possess a siderophore-mediated iron acquisition system. We demonstrated the presence of receptors for hemoglobin, lactoferrin and transferrin by measuring the binding of biotinylated hemoglobin, lactoferrin and transferrin to iron-starved P. haemolytica lysed whole culture on nitrocellulose by using streptavidin-con ed horseradish peroxidase. We also demonstrated that only ferrous sulfate (and ferric chloride) repressed the expression of the FbpA but none of the other divalent metal ions studied repressed the expression of FbpA. These results suggest that the iron-acquisition system is specific for ferric and ferrous ions only.