Submitted to: Biochemistry and Molecular Biology Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/13/2003
Publication Date: 3/20/2003
Citation: SMITH, R.A., TABATABAI, L.B. FIBRONECTIN-BINDING ACTIVITY AND IN VITRO DIFFERENTIAL EXPRESSION OF MANNHEIMIA HAEMOLYTICA IMMUNOGLOBULIN-BINDING PROTEIN. The FASEB JOURNAL. 2003. v. 17. Abstract #632.8.
Technical Abstract: Mannheimia haemolytica is the primary causative agent of bovine respiratory disease (BRD) or "shipping fever". Bacterial immunoglobulin-binding protein (IgBP) expression is known to play a role in the pathogenesis of a variety of organisms. We previously identified a membrane-associated and a soluble form of M. haemolytica serotype 1 (ST1) 74 kDa IgBP. Flow cytometry confirmed surface expression of the IgBP on whole cell M. haemolytica. Immune sera from convalescent cattle showed an increased antibody response to the IgBP when compared to sera from naïve or acutely infected cattle as seen by Western blot. To determine whether the IgBP was also an extracellular matrix-binding protein, fibronectin, collagen and fibrinogen were checked for binding to the IgBP in a far-Western blot. We also investigated the effect of altering growth conditions on the in vitro expression of the IgBP by supplementing RPMI-1640 with 2,2'-dipyridyl (to chelate free exogenous iron) or with 10% fetal bovine sera or changing the incubation temperature from 37C to 40C. The M. haemolytica IgBP was differentially expressed under these conditions. Our results show that IgBP not only binds bovine Fc IgG, but also binds bovine fibronectin. This is a significant finding and implies that M. haemolytica IgBP binding to fibronectin could potentially be a mechanism for M. haemolytica to attach to airway epithelial cells and that an immune response to the 75 kDa IgBP may play a role in protection from M. haemolytica infection. The M. haemolytica IgBP may play an important role in future vaccine preparations.