title: In vitro excystation of Cryptosporidium muris oocysts and viability of released sporozoites in different incubation media.
abstract: This study aimed to evaluate and document the excystation process of Cryptosporidium muris oocysts in various incubation media, and to monitor the behaviour of excysting and freshly excysted sporozoites. A test of oocyst viability, using fluorescent double staining with fluorescein diacetate and propidium iodide, was performed prior to each experimental assay. Light microscope observations confirmed that relatively often only three sporozoites were released; the fourth one either left the oocyst later together with a residual body or remained trapped within the oocyst wall. These results suggest that successful oocyst excystation is not limited by the viability of all four sporozoites. Darkening of oocysts to opaque and their specific movement (the so-called "oocyst dancing") preceded the final excystation and liberation of sporozoites, while the dormant oocysts appeared refractive. The process of excystation in C. muris is not gradual as generally described in cryptosporidia but very rapid in an eruptive manner. Experiments were performed using oocysts stored at 4 °C for various time periods, as well as oocysts freshly shed from host rodents (Mastomys coucha) of different ages. The most suitable medium supporting high excystation rate (76 %) and prolonged motility of sporozoites was RPMI 1640, enriched with 5 % bovine serum albumin (BSA). Our results emphasize that to reliably evaluate the success of in vitro excystation of cryptosporidia, not only the number of released sporozoites in a set time period should be taken into consideration but also their subsequent activity (motility), as it is expected to be essential for the invasion of host cells.
authors.affiliation: Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37, Brno, Czech Republic. jankam@sci.muni.cz.
authors.forename: Janka
authors.initials: J
authors.lastname: Melicherová
authors.affiliation: Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37, Brno, Czech Republic.
authors.forename: Veronika
authors.initials: V
authors.lastname: Mazourová
authors.affiliation: Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37, Brno, Czech Republic.
authors.forename: Andrea
authors.initials: A
authors.lastname: Valigurová
mesh_terms: D000818:Animals; D003458:Cryptosporidium / Q000187:drug effects* / Q000502:physiology*; D003470:Culture Media / Q000494:pharmacology*; D050296:Microbial Viability / Q000187:drug effects; D033661:Oocysts / Q000502:physiology*; D011419:Propidium; D051381:Rats; D034101:Sporozoites / Q000187:drug effects / Q000502:physiology
chemical_list: D003470:Culture Media; D011419:Propidium
keywords: Cryptosporidium muris; Excystation rate; Motility; Oocyst; Sporozoite; Viability test