The Role of the Arcanobacterium pyogenes Fibronectin Binding Proteins in Adhesion to Host Epithelial Cells.

M. A. Link, B. H. Jost, J. G. Songer, and S. J. Billington. Department of Veterinary Science and Microbiology, The University of Arizona, Tucson, Az.

Arcanobacterium pyogenes is often found as a commensal bacterium on the mucus membranes of ruminants, pigs and other domestic animals. However, in its role as an opportunistic pathogen, A. pyogenes is associated with suppurative infections such as mastitis and hepatic abscesses. In addition to pyolysin, a pore-forming, cholesterol binding toxin and two neuraminidases, A. pyogenes expresses a number of other putative virulence factors, including its ability to bind to host epithelial cells. An open reading frame encoding a putative fibronectin binding protein, fbpA, was cloned from a lGEM12 library of A. pyogenes genomic DNA. Sequencing revealed that fbpA displayed similarity to several extracellular matrix binding proteins, including streptococcal fibronectin binding proteins prft2, fnb, fnbB, and a Staphylococcus aureus collagen adhesin, cna. In some mucosal bacteria, the first step in pathogenesis, adherence, is mediated by a fibronectin binding protein, and we are currently undertaking studies to determine whether fbpA has a role in mediating A. pyogenes adherence to host epithelial cells.