| Most enterotoxigenic Escherichia coli (ETEC) isolated from neonatal cattle contain the colonization factor antigen, K99. The K99 pili are necessary for the bacteria to bind to the host lipoprotein receptor, N-glycolylneuraminic acid-GM3 (NeuGc-GM3), in the small intestine. The resulting ETEC infection, enteric colibacillosis, causes diarrhea, weight loss, and death in the host. When the binding interaction between the ETEC and host cell is inhibited, the bacteria cannot proliferate and release their toxins that cause the disease in the gut of the host. Previous studies used antibodies to block ETEC pili on the bacterial cell surface, but little work has been done using the K99 antigen to block the GM3 receptors on the host cells. The binding activity of native K99 protein was studied and then a recombinant K99 protein was designed with a similar binding activity as its native counterpart. Competitive binding assays were used to demonstrate that the recombinant protein, 145, had a similar binding activity to native K99. Based on the results of the binding assays it was concluded that recombinant protein 145 could be used as an effective agent to block the host GM3 receptors and inhibit K99 + ETEC infections in cattle. |
