Abstract
Rhoptry organelles from sporozoites of the apicomplexan parasite Eimeria tenella contain at least 60 independent polypeptides that can be resolved by two-dimensional gel electrophoresis. Rhoptries from three species of Eimeria that infect chickens share very few antibody cross-reactive epitopes, and there is poor conservation of epitopes among three distinct asexual generations of zoites within the developmental life cycle of a single parasite, E. tenella.