Characterization of protective antigen CbpB as an adhesin and a plasminogen-binding protein of Erysipelothrix rhusiopathiae.

Erysipelothrix rhusiopathiae is the causative agent of animal erysipelas and human erysipeloid. E. rhusiopathiae CbpB has been reported to be a protective antigen, but its pathogenic roles are not known. The aim of this study was to evaluate the ability of CbpB to act as an adhesin in E. rhusiopathiae adhesion to porcine endothelial cells as well as a host plasminogen- and fibronectin- binding protein. Recombinant CbpB (rCbpB) was successfully obtained, and it was found that E. rhusiopathiae CbpB was located on the cell surface of E. rhusiopathiae. Moreover, CbpB exhibited binding activity to porcine endothelial cells. Recombinant CbpB successfully bound to host plasminogen but was unable to bind to fibronectin. In conclusion, our work suggested that CbpB is a virulence factor of E. rhusiopathiae.