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This Article Full Text (PDF) All Versions of this Article: jas.2008-1492v1 87/5/1787    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Murphy, R. G. L. Articles by Belk, K. E. Search for Related Content PubMed PubMed Citation Articles by Murphy, R. G. L. Articles by Belk, K. E.

Alkaline hydrolysis of mouse-adapted scrapie for inactivation and disposal of prion-positive material

Ryan G. L. Murphy^*, John A. Scanga^*, Barbara E. Powers, John L. Pilon, Kurt C. VerCauteren, Paul B. Nash, Gary C. Smith^* and Keith E. Belk^*

^* Center for Meat Safety and Quality, Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523 , Veterinary Diagnostics Laboratory, Colorado State University, Fort Collins, CO 80523 USDA-APHIS-WS-National Wildlife Research Center, Fort Collins, CO 80521

keith.belk{at}colostate.edu

Abstract

Prion diseases such as bovine spongiform encephalopathy, chronic wasting disease, and scrapie pose serious risks to human and animal health due to a host of disease-specific factors, including the resistance of infectious prions (PrP^Sc) to natural degradation and to most commercial inactivation procedures. In an attempt to address this concern, a mouse model was used to compare the efficacy of an alkaline hydrolysis process to a simulated continuous-flow rendering treatment for disposal of PrP^Sc-infected biological material. Female C57/BL6 mice (N=120) were randomly divided into 4 treatment groups (n=30) and each mouse was injected intraperitoneally with their designated treatment inoculum. Treatment Groups 1 and 2 served as the positive and negative controls, respectively. Group 3 was inoculated with rendered scrapie-positive mouse brain material to investigate the effectiveness of simulated continuous-flow rendering practices to reduce or eliminate PrP^Sc. Group 4 was inoculated with hydrolyzed scrapie-positive mouse brain material to determine the sterilizing effect of alkaline hydrolysis on PrP^Sc. Mice were monitored for overt signs of disease and those showing clinical signs were euthanized to prevent undue suffering. Brains were obtained from all mice that died (or were euthanized) and analyzed with an ELISA for the presence of PrP^Sc. Results indicated that the continuous-flow rendering treatment used for preparing the rendering treatment group inoculum failed to completely eliminate PrP^Sc. Rendering delayed, but did not stop, clinical mouse-adapted scrapie transmission. Compared to positive controls, the rendering treatment group experienced an approximate 45-d average delay in days to death (250 d vs. 205 d for positive controls; P < 0.0001) and a death loss of 73.9% (P = 0.0094). Positive controls suffered 100% death loss. The results validated the efficacy of the alkaline hydrolysis treatment to inactivate all PrP^Sc as no alkaline hydrolysis treatment group mice succumbed to the disease (P < 0.0001). Based on our results, alkaline hydrolysis should be considered by the animal rendering and beef packing industries as an alternative to incineration, landfill burial, and rendering for disposing of biological material potentially infected or contaminated with prion disease.

Key Words: alkaline hydrolysis • commercial rendering • mouse model • prion inactivation