title: Inactivation of template-directed misfolding of infectious prion protein by ozone.
abstract: Misfolded prions (PrP(Sc)) are well known for their resistance to conventional decontamination processes. The potential risk of contamination of the water environment, as a result of disposal of specified risk materials (SRM), has raised public concerns. Ozone is commonly utilized in the water industry for inactivation of microbial contaminants and was tested in this study for its ability to inactivate prions (263K hamster scrapie = PrP(Sc)). Treatment variables included initial ozone dose (7.6 to 25.7 mg/liter), contact time (5 s and 5 min), temperature (4°C and 20°C), and pH (pH 4.4, 6.0, and 8.0). Exposure of dilute suspensions of the infected 263K hamster brain homogenates (IBH) (0.01%) to ozone resulted in the in vitro destruction of the templating properties of PrP(Sc), as measured by the protein misfolding cyclic amplification (PMCA) assay. The highest levels of prion inactivation (≥4 log(10)) were observed with ozone doses of 13.0 mg/liter, at pH 4.4 and 20°C, resulting in a CT (the product of residual ozone concentration and contact time) value as low as 0.59 mg · liter(-1) min. A comparison of ozone CT requirements among various pathogens suggests that prions are more susceptible to ozone degradation than some model bacteria and protozoa and that ozone treatment may be an effective solution for inactivating prions in water and wastewater.
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Ning
authors.initials: N
authors.lastname: Ding
authors.forename: Norman F
authors.initials: NF
authors.lastname: Neumann
authors.forename: Luke M
authors.initials: LM
authors.lastname: Price
authors.forename: Shannon L
authors.initials: SL
authors.lastname: Braithwaite
authors.forename: Aru
authors.initials: A
authors.lastname: Balachandran
authors.forename: Miodrag
authors.initials: M
authors.lastname: Belosevic
authors.forename: Mohamed Gamal
authors.initials: MG
authors.lastname: El-Din
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects; D006224:Cricetinae; D004202:Disinfectants / Q000378:metabolism*; D004203:Disinfection / Q000379:methods; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D010126:Ozone / Q000378:metabolism*; D018620:PrPSc Proteins / Q000378:metabolism*; D017510:Protein Folding / Q000187:drug effects*; D013696:Temperature; D013997:Time Factors
chemical_list: D004202:Disinfectants; D018620:PrPSc Proteins; D010126:Ozone