Vaccination of turkey poults against pathogenic Escherichia coli.

A vaccine made of bacterial membranes which form vesicles has been developed in our laboratory and found to be effective in protecting chickens against challenge with pathogenic E. coli. In the present study we monitored maternal anti-5. coli antibody in turkey poults and found that although at hatch the antibody titre was relatively high, it decreased gradually to a low level by 14 days of age and remained low up to 31 days of age. Both intramuscular and subcutaneous vaccination with membrane vesicles (MV) resulted in increased antibody titres. Poults with high antibody titres could survive challenge with the pathogenic bacteria. Serum from vaccinated poults reduced E. coli bacterial growth rate when added to the growth medium at a high concentration, whereas serum from non-vaccinated poults did not. Lymphocytes from vaccinated poults responded with an increased rate of blastogenesis when MV was added to the cultures. Lymphocytes from non-vaccinated poults were not stimulated to blastogenesis. We concluded that MV can be used as a vaccine to render poults resistant to E. coli by evoking antibody production, stimulating the bacterial-lysis activity of complement, stimulating T cells to proliferate and stimulating cytotoxic T cells involved in disease resistance.