title: Viability staining and animal infectivity of Cryptosporidium andersoni oocysts after long-term storage.
abstract: Preservation of biological properties of oocysts during the storage is critical for experimental work. Stomach species of cryptosporidia are less resistant against external influences, and their infectivity decreases rapidly in comparison with intestinal cryptosporidia. Cryptosporidium andersoni oocysts lost their infectivity for gerbil (Meriones unguiculatus) after 7 months storage in deionised water (DW) or in 2.5% potassium dichromate solution (PDS). Evaluation of oocyst viability by flow cytometry indicates higher percentage of viable oocysts stored in PDS than in DW, particularly after 6 months of storage. However, direct counting using fluorescent microscope revealed that these results are false and are influenced by the change of staining properties during the storage in PDS. Moreover, the examination of oocyst integrity by flow cytometry revealed that oocysts preserved in PDS kept their wall integrity longer than those stored in DW, and this fact should be taken into consideration during quantification of oocyst survival.
authors.affiliation: Institute of Parasitology, Academy of Sciences of the Czech Republic, Branisovská 31, 370 05, Ceské Budejovice, Czech Republic. kvac@centrum.cz
authors.forename: Martin
authors.initials: M
authors.lastname: Kvác
authors.forename: Dana
authors.initials: D
authors.lastname: Kvetonová
authors.forename: Jirí
authors.initials: J
authors.lastname: Salát
authors.forename: Oleg
authors.initials: O
authors.lastname: Ditrich
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000502:physiology*; D003458:Cryptosporidium / Q000502:physiology*; D005849:Gerbillinae; D033661:Oocysts / Q000502:physiology*; D013048:Specimen Handling; D013194:Staining and Labeling; D013997:Time Factors