bovine enterotoxigenic escherichia coli ag43 as a potential vaccine for calf colibacillosis

Enterotoxigenic escherichia coli (etec) is the most common bacterial cause of diarrhea in human and farm animals. in spite of the global importance of etec infections, there is no vaccine available for widespread protection. recent studies are directed toward recognizing genomic conserved antigens of e. coli, including autotransporter proteins. antigen 43 (ag43) is an autotransporter protein that causes auto aggregation and biofilm formation, with a low frequency in commensal strains. it is among a few genes that distinguish etec pathotypes from nonpathogenic strains, which are also important in development of efficient vaccine. in the current study, a passenger domain of ag43 in a bovine etec strain was amplified and cloned into a pet-28a(+) plasmid. the recombinant ag43 was purified via a ni-nta agarose column and verified by western blotting. female balb/c mice were immunized and their infant mice were challenged by the same strain to evaluate the protection effects. a significant increased level of serum specific antibodies was observed and a potential protection was achieved. the results indicated that the passenger domain of ag43 protein can be introduced as a broad valuable antigen in development of calf colibacillosis vaccine.