In vitro and in vivo immunolabeling of sporozoites, schizonts, and sexual stages of Eimeria acervulina and E. tenella by a species- and stage-cross-reactive monoclonal antibody.

A cross-reactive monoclonal antibody (mAb), designated 1205, was used to study redistribution, parasitophorous vacuole (PV) incorporation, and in situ antigen production during the intracellular parasite development of Eimeria acervulina and E. tenella. Western-blot analysis of sporozoite preparations showed that the mAb recognized antigenic bands at 55 and 80 kDa. Indirect immunofluorescent antibody (IFA) labeling of sporozoites produced an internal dot pattern. Immunogold electron microscopy (IM) showed labeling of dense granules within sporozoites. The IFA pattern changed to a general-internal label in immature schizonts followed by a surface-tip pattern in mature merozoites both in vitro and in vivo. IM of the asexual stages revealed the same labeling pattern for the in vivo development of both species, and labeling of rhoptries was seen. In vitro, the PV membrane together with amorphous material within the PV was labeled by IFA during schizont development for E. tenella. No IM labeling of either the PV membrane or material within the PV was observed. Sexual stages seen in vivo for both species had the general-internal IFA pattern.