Haemagglutinating and Adhesive Properties Associated with the K99 Antigen of Bovine Strains of Escherichia coli

Abstract

The K99 antigen common to some bovine strains of E. coli caused mannose-resistant hemagglutination of sheep erythrocytes; it was apparently responsible for the attachment of K99-positive bacteria to calf brush-border preparations as strains grown at 18.degree. C did not produce K99 antigen, cause hemagglutination or attach to brush borders. Also, a K12 (K99+) recombinant strain showed hemagglutinating activity and attachment to brush borders; before it received the K99 plasmid, the recipient strain was negative in both respects. Cell-free extracts of K99 antigen showed hemagglutinating activity and inhibited the attachment of K99-positive organisms to brush borders. K99 antigen appears to be a virulence determinant in the pathogenesis of neonatal calf diarrhea. It is readily demonstrated by hemagglutination and brush border attachment tests.