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Xu S.,University of Alberta | Xu S.,Agriculture and Agri Food Canada | Reuter T.,Alberta Agriculture and Rural Development | Gilroyed B.H.,Agriculture and Agri Food Canada | And 8 more authors.
Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering | Year: 2013

Composting may be a viable alternative to rendering and land filling for the disposal of specified risk material (SRM) provided that infectious prion proteins (PrPTSE) are inactivated. This study investigated the degradation of SRM and the fate of scrapie prions (PrPSc) over 28days in laboratory-scale composters, with and without feathers in the compost matrices. Compost was mixed at day 14 to generate a second heating cycle, with temperatures exceeding 65C in the first cycle and 50C in the second cycle. Approximately 63% and 77% of SRM was degraded after the first and second cycles, respectively. Inclusion of feathers in the compost matrices did not alter compost properties during composting other than increasing (P < 0.05) total nitrogen and reducing (P < 0.05) the C/N ratio. However, addition of feathers enhanced (P < 0.05) SRM degradation by 10% upon completion of experiment. Scrapie brain homogenates were spiked into manure at the start of composting and extracted using sodium dodecyl sulphate followed by detection using Western blotting (WB). Prior to composting, PrPSc was detectable in manure with 1-2 log10 sensitivity, but was not observable after 14 or 28days of composting. This may have been due to either biological degradation of PrPSc or the formation of complexes with compost components that precluded its detection. © 2013 Taylor & Francis Group, LLC. Source


Xu S.,Agriculture and Agri Food Canada | Reuter T.,Alberta Agriculture and Rural Development | Gilroyed B.H.,University of Guelph | Mitchell G.B.,Canadian Food Inspection Agency | And 10 more authors.
Environmental Science and Technology | Year: 2014

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 (PrPCWD), and bovine spongiform encephalopathy (PrPBSE) in lab-scale composters and PrP263K in field-scale compost piles. Western blotting (WB) indicated that PrP263K, PrPCWD, and PrPBSE 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 PrP263K and 3 log10 in PrP CWD. Enrichment for proteolytic microorganisms through the addition of feather keratin to compost enhanced degradation of PrP263K and PrPCWD. For field-scale composting, stainless steel beads coated with PrP263K 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 PrP263K infectivity. Our findings show that composting reduces PrPTSE, resulting in one 50% infectious dose (ID 50) remaining in every 5600 kg of final compost for land application. With these considerations, composting may be a viable method for SRM disposal. © 2014 American Chemical Society. Source


Dudas S.,Canadian Food Inspection Agency Lethbridge Laboratory | Yang J.,Canadian Food Inspection Agency Lethbridge Laboratory | Yang J.,Agriculture and Agri Food Canada | Yang J.,China Agricultural University | And 5 more authors.
PLoS ONE | Year: 2010

The epidemiology and possibly the etiology of bovine spongiform encephalopathy (BSE) have recently been recognized to be heterogeneous. In particular, three types [classical (C) and two atypical (H, L)] have been identified, largely on the basis of characteristics of the proteinase K (PK)-resistant core of the misfolded prion protein associated with the disease (PrPres). The present study was conducted to characterize the 17 Canadian BSE cases which occurred prior to November 2009 based on the molecular and biochemical properties of their PrPres, including immunoreactivity, molecular weight, glycoform profile and relative PK sensitivity. Two cases exhibited molecular weight and glycoform profiles similar to those of previously reported atypical cases, one corresponding to H-type BSE (case 6) and the other to L-type BSE (case 11). All other cases were classified as C-type. PK digestion under mild and stringent conditions revealed a reduced protease resistance in both of these cases compared to the C-type cases. With Western immunoblotting, N-terminal-specific antibodies bound to PrPres, from case 6 but not to that from case 11 or C-type cases. C-terminal-specific antibodies revealed a shift in the glycoform profile and detected a fourth protein fragment in case 6, indicative of two PrPres, subpopulations in H-type BSE. No mutations suggesting a genetic etiology were found in any of the 17 animals by sequencing the full PrP-coding sequence in exon 3 of the PRNP gene. Thus, each of the three known BSE types have been confirmed in Canadian cattle and show molecular characteristics highly similar to those of classical and atypical BSE cases described from Europe, Japan and the USA. The occurrence of atypical cases of BSE in countries such as Canada with low BSE prevalence and transmission risk argues for the occurrence of sporadic forms of BSE worldwide. © 2010 Dudas et al. Source

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