SUSCEPTIBILITY TO EIMERIA-TENELLA OF CHICKENS AND CHICKEN EMBRYOS OF PARTLY INBRED LINES POSSESSING HOMOZYGOUS MAJOR HISTOCOMPATIBILITY COMPLEX HAPLOTYPES

Susceptibility to Eimeria tenella infection of chicken embryos and chi ckens of partly inbred lines possessing different major histocompatibi lity complex haplotypes was investigated. Chicken embryos of line H-B2 possessing B2 homozygous haplotype showed lower mortality and higher oocyst production than embryos of line H-B15 possessing B-15 homozygou s haplotype. Embryos of line H-B2 chickens were considered more resist ant to E. tenella infection than those of line H-B15. Seven days after 10-day-old chickens were infected with E. tenella, the two lines show ed no significant differences in percent body-weight gain, cecal lesio n score, and oocyst production; they differed significantly only in ce cal shrinkage. Results suggest that the B system affects chicken embry os and chickens differently in susceptibility to E. tenella infection.