title: Biodegradation of prions in compost.
abstract: Composting may serve as a practical and economical means of disposing of specified risk materials (SRM) or animal mortalities potentially infected with prion diseases (transmissible spongiform encephalopathies, TSE). Our study investigated the degradation of prions associated with scrapie (PrP(263K)), chronic waste disease (PrP(CWD)), and bovine spongiform encephalopathy (PrP(BSE)) in lab-scale composters and PrP(263K) in field-scale compost piles. Western blotting (WB) indicated that PrP(263K), PrP(CWD), and PrP(BSE) were reduced by at least 2 log10, 1-2 log10, and 1 log10 after 28 days of lab-scale composting, respectively. Further analysis using protein misfolding cyclic amplification (PMCA) confirmed a reduction of 2 log10 in PrP(263K) and 3 log10 in PrP(CWD). Enrichment for proteolytic microorganisms through the addition of feather keratin to compost enhanced degradation of PrP(263K) and PrP(CWD). For field-scale composting, stainless steel beads coated with PrP(263K) were exposed to compost conditions and removed periodically for bioassays in Syrian hamsters. After 230 days of composting, only one in five hamsters succumbed to TSE disease, suggesting at least a 4.8 log10 reduction in PrP(263K) infectivity. Our findings show that composting reduces PrP(TSE), resulting in one 50% infectious dose (ID50) remaining in every 5600 kg of final compost for land application. With these considerations, composting may be a viable method for SRM disposal.
authors.affiliation: Agriculture and Agri-Food Canada, Lethbridge Research Centre , Lethbridge, Alberta T1J 4B1, Canada.
authors.forename: Shanwei
authors.initials: S
authors.lastname: Xu
authors.forename: Tim
authors.initials: T
authors.lastname: Reuter
authors.forename: Brandon H
authors.initials: BH
authors.lastname: Gilroyed
authors.forename: Gordon B
authors.initials: GB
authors.lastname: Mitchell
authors.forename: Luke M
authors.initials: LM
authors.lastname: Price
authors.forename: Sandor
authors.initials: S
authors.lastname: Dudas
authors.forename: Shannon L
authors.initials: SL
authors.lastname: Braithwaite
authors.forename: Catherine
authors.initials: C
authors.lastname: Graham
authors.forename: Stefanie
authors.initials: S
authors.lastname: Czub
authors.forename: Jerry J
authors.initials: JJ
authors.lastname: Leonard
authors.forename: Aru
authors.initials: A
authors.lastname: Balachandran
authors.forename: Norman F
authors.initials: NF
authors.lastname: Neumann
authors.forename: Miodrag
authors.initials: M
authors.lastname: Belosevic
authors.forename: Tim A
authors.initials: TA
authors.lastname: McAllister
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D001681:Biological Assay; D015153:Blotting, Western; D002417:Cattle; D006224:Cricetinae; D005260:Female; D008647:Mesocricetus; D050505:Mutant Proteins / Q000378:metabolism; D011328:Prions / Q000378:metabolism*; D017510:Protein Folding; D012987:Soil / Q000737:chemistry*
chemical_list: D050505:Mutant Proteins; D011328:Prions; D012987:Soil