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Evidence for degradation of abnormal prions in tissues from scrapie affected sheep during composting
EP38509
Poster Title: Evidence for degradation of abnormal prions in tissues from scrapie affected sheep during composting
Submitted on 22 Mar 2022
Author(s): Hongsheng Huang, J. Lloyd Spencer, Andrei Soutyrine, Jiewen Guan, Jasmine Rendulich and Aru Balachandran
Affiliations: Canadian Food Inspection Agency, Ottawa laboratory - Fallowfield
This poster was presented at Keystone Symposia, TSE conference, Snowbird, 2005
Poster Views: 222
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Poster Information
Abstract: The causative agent of Transmissible Spongiform Encephalopathies (TSEs), believed to be abnormal prion protein (PrPSc), is highly resistant to decontamination and disinfection by conventional chemical and physical procedures. We conducted composting studies and an in vitro test tube simulation study to assess the influence of these processes on degradation of PrPSc of scrapie sheep. In the in vitro study, central nervous system (CNS) tissues from 4 scrapie positive animals were suspended in physiological saline and were incubated at 630C for up to 3 months. Scrapie PrPSc were detected in all specimens prior to incubation using Western blot (WB) (following PrPSc enrichment using sodium phosphotungstic acid precipitation) and ELISA (Bio-Rad). After one month of incubation, tissues from two sheep tested negative by both tests but based on WB, two others remained positive at a reduced level for 3 months. In the first compost experiment, various tissues including CNS and lymphoid tissues from two scrapie sheep were placed in fiberglass mesh bags where they were covered with sawdust. In some cases, the tissues were placed in open petri dishes within the mesh bags. These specimens were then buried in the upper third of a compost pile that was composed of cow manure and straw. Compost temperatures were above 600C for about 2 weeks and then slowly declined to room temperature. After 108 days in the compost pile, tissues were dry and significantly reduced in weight. Remaining tissues and surrounding saw dust were collected and the concentrations of the samples were adjusted to be comparable to the controls. The PrPSc could be detected prior to, but not after composting by either WB or ELISA. In the second experiment, 5 CNS specimens from one scrapie positive sheep were placed in mesh bags where they were surrounded by a layer of sawdust. They were buried in a compost pile where conditions were similar to those in the first pile. After 148 days in the compost pile, 4 of 5 specimens were weakly positive by WB but all specimens were negative by ELISA. Based on PCR tests that were designed to detect a broad range of microbes in specimens, there was evidence that thermophilic microbes had persisted throughout the 3 months of incubation in the in vitro study and it is suggested that thermophilic microbes had a role in degradation of PrPSc during composting. Summary: The causative agent of Transmissible Spongiform Encephalopathies (TSEs), believed to be abnormal prion protein (PrPSc), is highly resistant to decontamination and disinfection by conventional chemical and physical procedures. We conducted composting studies and an in vitro test tube simulation study to assess the influence of these processes on degradation of PrPSc of scrapie sheep. After composting, the abnormal prion was not detectable by a highly sensitive Western blot analysis or ELISA.References: Huang H (senior and corresponding author), Spencer JL, Soutyrine A, Guan J, Rendulich J, Balachandran A. 2007. Evidence for degradation of abnormal prion protein in tissues from scrapie affected sheep during composting. Can. J. Vet. Res. 70: 34-40.Report abuse »
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