Anti-idiotypic antibodies were raised in rabbits against four
monoclonal antibodies with specificity for the surface
antigenic determinants of Eimeria tenella sporozoites, the infective stage of the coccidial parasite. Two of the
monoclonal antibodies (1073 and 15-1) transferred passive protection in chickens against E. tenella
infection. The polyclonal anti-idiotype antibody preparations against protective
monoclonal antibodies contained specificities for the paratope-associated idiotypes of these
monoclonal antibodies, as assessed by the competitive inhibition of binding of the homologous idiotype-anti-idiotype by the sporozoite
antigen. Competitive inhibition of binding of homologous idiotype-anti-idiotype by the parasite
antigen was not observed when the anti-idiotype antibody preparations against
monoclonal antibodies 1546 and 1096 were tested. The anti-idiotype 1073 and 15-1
antibodies functioned as surrogate
antigens in vivo when used for vaccination of young chickens, as evidenced by the induction of partial protective immunity against subsequent challenge
infection with virulent parasites and induction of antisporozoite
antibodies. These data clearly support the view that
anti-idiotypic antibodies raised against the paratope-associated idiotypes can mimic pathogen
antigens and therefore can provide a possible alternative approach for the vaccination of chickens against
coccidiosis.