Cloning and expression in Escherichia coli of a protective antigen of Erysipelothrix rhusiopathiae.

Erysipelothrix rhusiopathiae is a primary pathogen of swine and turkeys and sporadic cause of disease in a variety of other hosts, including humans. A genomic library of the highly virulent strain of E. rhusiopathiae E1-6P was constructed in the expression-cloning vector lambda gt11 and screened with serum from a pig convalescent from an E. rhusiopathiae experimental infection. Immunoreactive clones were screened for their ability to protectively immunized mice. Two clones, lambda gt11/ersA and lambda gt11/ersB, were obtained that protected mice against challenge with E. rhusiopathiae E1-6P. Antisera against the recombinant clones reacted with polypeptides of molecular weights 66,000, 64,000, and 43,000 in detergent-solubilized surface antigen preparations and whole-cell lysates of E. rhusiopathiae. These polypeptides were also the major antigens recognized by convalescent pig serum when reacted with the same preparations. Western immunoblot and Southern blot analysis revealed that the cloned genes and gene products were present in all of the E. rhusiopathiae strains tested.