An in vitro model for assessing effective scrapie decontamination

• Published in: Veterinary microbiology Vol. 207; pp. 138 - 142
• Main Authors: Gough, K.C., Baker, C.A., Maddison, B.C.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-08-2017; Elsevier BV
• Subjects: Animal diseases; Animals; Chlorine; Concrete; Construction Materials; Decontamination; Decontamination - methods; Dilution; Disinfection; Farms; Fomite; Fomites; Housing, Animal; Infectivity; Prion; Prion protein; Prions; Protein folding; Protein seeding; PrPSc Proteins - chemistry; Scrapie; sPMCA; Surface Properties; Prion; Scrapie; sPMCA; Decontamination; Fomite
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/j.vetmic.2017.05.018

•Scrapie prions which have been shed from infected sheep and goats are extremely difficult to decontaminate within the farm environment.•Scrapie infectivity was modelled using the Protein Misfolding Cyclic Amplification (PMCA) assay with reference to a dilution of scrapie positive brain material.•PMCA was used to determine the effectiveness of different decontamination methodologies as applied to scrapie contaminated concrete surfaces.•Current recommended methods using either 20,000 ppm free chlorine or 2M NaOH, did not result in full reduction in scrapie seeding activity.•Effective reduction of concrete bound scrapie seeding activity was achieved after 4 applications of 20,000 ppm free chlorine.
Scrapie infectivity enters the environment via a multiplicity of routes from infected animals. Environmentally associated scrapie persists on farms when infected animals have been removed and is particularly resistant to disinfection. Infectivity within the farm is not adequately removed by current recommended guidelines for farm decontamination. We describe an in vitro method for modelling decontamination, specifically the removal of scrapie prions from the surface of concrete fomites within buildings that have housed scrapie infected animals. Concrete that had been spiked with low amounts of a diluted scrapie positive brain homogenate was sampled before and after decontamination. Extracts were used to seed a semi-quantitative serial protein misfolding cyclic amplification assay (sPMCA). We demonstrate that methods currently recommended for prion decontamination result in inadequate reduction of prion seeding activity within this in vitro assay. Effective treatment was achieved using repeat dosing of surfaces with 20,000ppm available chlorine for 4h.