PROTECTIVE ORAL IMMUNIZATION OF CHICKENS AGAINST EIMERIA-TENELLA WITHSPOROZOITE SURFACE-ANTIGENS

Antigens were extracted from the surface of Eimeria tenella sporozoite s with a solution containing Triton X 100 (1%), sodium dodecyl sulphat e (0.5%) Na deoxycholate (1%) and EDTA (1 mM). After removal of the de tergents, these surface antigen preparations conferred an immunity tha t protected chickens against a subsequent infection (10(4) sporulated oocysts). The best results were obtained after two 250 mug injections of Al(OH)3 adsorbed antigens (oocyst output per g caecal material on D ay 7 post infection: 2.39 x 10(7) +/- 0.32 x 10(7) oocysts for control s and 7.37 X 10(6) +/- 3.19 x 10(6) oocysts for vaccinated birds) and after four gastric intubations of liposome entrapped antigens (oocyst output on Day 7 postinfection: 2.75 x 10(6) +/- 2.02 x 10(6) g-1 caeca l material ). These results represented respectively 70 and 88% protec tion indexes. Studies on the systemic and local antibody response afte r one or several infections of chickens with the parasite indicated at least 20 different molecules in the detergent antigens which are clas sified after immunoblotting according to their properties.