ABSTRACT:

Approximately forty percent of travellers to developing countries experience diarrhoea caused by enterotoxigenic Escherichia coli (ETEC). Studies have shown that the ingestion of specific antibodies can provide protection against ETEC infection. The objective of this project is to develop a hyperimmune bovine colostrum (HBC) product, which will protect against ETEC infections. Pregnant cows were vaccinated with several inactivated monovalent and multivalent vaccines containing strains expressing the major colonisation factor antigens (CFAI, II and IV). Colostrum from cows receiving the multivalent vaccine had whole cell ELISA antibody titres of 570,000, 800,000 and 130,000 for CFA I, II and IV strains respectively. Immunoblots of HBC indicate specific responses to the CFA antigens. HBC from cows vaccinated with purified heat labile toxin (LTb) show ELISA titres of approximately 275,000. Although results indicate strong immunological responses to various protective antigens, the level of the response to different strains was variable. Future studies will investigate factors affecting this variability as well as the efficacy of the HBC.