title: Nucleic acid stains as indicators of Cryptosporidium parvum oocyst viability.
abstract: We developed nucleic acid dye staining methodology for untreated, heat-treated and chemically inactivated C. parvum oocysts. The nucleic acid staining was compared to in vitro excystation and animal infectivity using split samples of oocysts. Among the nucleic acid stains tested, SYTO-9, hexidium and SYTO-59 stained the oocysts consistently, and the staining was related to the infectivity of the oocysts to neonatal CD-1 mice but not to in vitro excystation. The nucleic acid viability assay was used to determine log-inactivations of the oocysts after treatment with ozone, chlorine, chlorine dioxide and combinations of different chemical disinfectants, and was found to indicate log-inactivation levels similar to that of animal infectivity. A combined immunofluorescence-nucleic acid staining assay was developed for the oocysts of C. parvum and this assay will be invaluable for the detection and viability of oocysts in the laboratory and in environmental samples.
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Canada. mike.belosevic@ualberta.ca
authors.forename: M
authors.initials: M
authors.lastname: Belosevic
authors.forename: R A
authors.initials: RA
authors.lastname: Guy
authors.forename: R
authors.initials: R
authors.lastname: Taghi-Kilani
authors.forename: N F
authors.initials: NF
authors.lastname: Neumann
authors.forename: L L
authors.initials: LL
authors.lastname: Gyürék
authors.forename: L R
authors.initials: LR
authors.lastname: Liyanage
authors.forename: P J
authors.initials: PJ
authors.lastname: Millard
authors.forename: G R
authors.initials: GR
authors.lastname: Finch
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D002713:Chlorine / Q000494:pharmacology; D017606:Chlorine Compounds; D004396:Coloring Agents; D003457:Cryptosporidiosis / Q000469:parasitology; D016785:Cryptosporidium parvum / Q000737:chemistry* / Q000254:growth & development*; D016054:DNA, Protozoan / Q000032:analysis*; D004202:Disinfectants / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D006358:Hot Temperature; D008297:Male; D051379:Mice; D009930:Organic Chemicals; D010087:Oxides / Q000494:pharmacology; D010126:Ozone / Q000494:pharmacology; D013194:Staining and Labeling
chemical_list: D017606:Chlorine Compounds; D004396:Coloring Agents; D016054:DNA, Protozoan; D004202:Disinfectants; D009930:Organic Chemicals; D010087:Oxides; C103389:SYTO 9; D002713:Chlorine; D010126:Ozone; C025109:chlorine dioxide