Development ofEimeria nieschulzi(Coccidia, Apicomplexa) Gamonts and Oocysts in Primary Fetal Rat Cells

Abstract

Thein vitroproduction of gametocytes and oocysts of the apicomplexan parasite genusEimeriais still a challenge in coccidiosis research. Until today, anin vitrodevelopment of gametocytes or oocysts had only been shown in someEimeriaspecies. For several mammalianEimeriaspecies, partial developments could be achieved in different cell types, but a development up to gametocytes or oocysts is still lacking. This study compares several permanent cell lines with primary fetal cells of the black rat (Rattus norvegicus) concerning the qualitativein vitrodevelopment of the rat parasiteEimeria nieschulzi. With the help of transgenic parasites, the developmental progress was documented. The selectedEimeria nieschulzistrain constitutively expresses the yellow fluorescent protein and a macrogamont specific upregulated red tandem dimer tomato. In the majority of all investigated host cells the development stopped at the second merozoite stage. In a mixed culture of cells derived from inner fetal organs the development of schizont generations I-IV, macrogamonts, and oocysts were observed in crypt-like organoid structures. Microgamonts and microgametes could not be observed and oocysts did not sporulate under air supply. By immunohistology, we could confirm that wild-typeE. nieschulzistages can be found in the crypts of the small intestine. The results of this study may be helpful for characterization of native host cells and for development of anin vitrocultivation system forEimeriaspecies.