EFFECT OF VIBRIO-CHOLERAE TOXIN ON ORAL IMMUNIZATION OF CHICKENS

Cholera toxin from Vibrio cholerae has been shown to increase the secr etory immune response when given orally with some antigens in mice and rabbits. The present study was designed to determine if cholera toxin was also an effective mucosal adjuvant in chickens. Tetanus toxoid wa s chosen as a model antigen, and response was measured by enzyme-linke d immunosorbent assays of intestinal excreta, bile samples, and serum samples. Chickens given 20 mug of tetanus toxoid had a significant sup pression of response when 20 or 50 ug of cholera toxin was given. Chic kens given 100 mug of tetanus toxoid appeared to be mucosally tolerant , but there was apparent abrogation of the mucosal tolerance when 20 o r 50 mug of cholera toxin was given. Cholera toxin apparently failed a s a mucosal adjuvant in chickens but may have some anti-mucosal tolero genic effect.