title: Studies on synchronous egress of coccidian parasites (Neospora caninum, Toxoplasma gondii, Eimeria bovis) from bovine endothelial host cells mediated by calcium ionophore A23187.
abstract: Neospora caninum, Toxoplasma gondii and Eimeria bovis are coccidian parasites of veterinary importance. Tachyzoites of N. caninum and T. gondii and sporozoites of E. bovis are able to invade and replicate in endothelial cells in vivo and in vitro. As it holds true for all eukaryotic cells, the survival of parasitized host cells and the parasites themselves should be dependent on ion balances, especially on extra- and intracellular calcium concentrations. Addition of the calcium ionophore A23187 reliably did release merozoites from mature N. caninum and T. gondii meronts grown in cultured primary bovine umbilical vein endothelial cells (BUVEC). Extent and time course of merozoite release depended on both, maturity of the meronts and concentration of the calcium ionophore. Attempts, however, to achieve synchronous release of merozoites from E. bovis first generation meronts by ionophore treatment failed, suggesting a different biological behaviour of this parasite. According to microscopical observations, the quite variable time of E. bovis macromeront maturation and a hampered merozoite exit owing to dense parasite-induced cytoskeleton elements surrounding the meront may be a reason for the lack of inducible synchronous release.
authors.affiliation: Institute of Parasitology, Justus Liebig University Giessen, D-35392 Giessen, Germany. jan-hillern.behrendt@vetmed.uni-giessen.de
authors.forename: Jan H
authors.initials: JH
authors.lastname: Behrendt
authors.forename: Anja
authors.initials: A
authors.lastname: Taubert
authors.forename: Horst
authors.initials: H
authors.lastname: Zahner
authors.forename: Carlos
authors.initials: C
authors.lastname: Hermosilla
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy / Q000469:parasitology*; D003048:Coccidiosis / Q000188:drug therapy / Q000469:parasitology / Q000662:veterinary*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004539:Eimeria / Q000187:drug effects*; D042783:Endothelial Cells / Q000469:parasitology; D007476:Ionophores / Q000494:pharmacology*; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008858:Microscopy, Phase-Contrast / Q000662:veterinary; D018688:Neospora / Q000187:drug effects; D021745:Sarcocystidae / Q000187:drug effects*; D014122:Toxoplasma / Q000187:drug effects
chemical_list: D015853:Cysteine Proteinase Inhibitors; D007476:Ionophores; D000001:Calcimycin; D007930:Leucine; C024974:E 64