Alkaline hydrolysis of mouse-adapted scrapie for inactivation and disposal of prion-positive material1

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 with 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 killed to prevent undue suffering. Brains were obtained from all mice that died (or were killed) and analyzed with an ELISA for the presence of PrP(Sc). Results indicated that the simulated 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 with positive controls, the rendering treatment group experienced an approximate 45-d average delay in days to death (250 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) because 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.

Inactivation of Geobacillus stearothermophilus spores by alkaline hydrolysis applied to medical waste treatment

“…Thacker (2004) indicates costs of $320 ton -1 , including those with steam, water, electricity, chemicals, labor, sanitary sewer and maintenance and repair. Similar values ($260-$310 ton -1 ) were obtained by Murphy et al (2009) using alkaline hydrolysis to dispose of animal tissues and carcasses during their study on prion inactivation. These costs do not include the initial capital investment.…”

“…Indeed, at 121 o C the thermal inactivation of spores generally follows a first order linear kinetics while under alkaline treatment, as described above, inactivation curves were non-linear. Some authors (Murphy et al, 2009;Thacker, 2004) estimated the costs for the alkaline hydrolysis treatment. Thacker (2004) indicates costs of $320 ton -1 , including those with steam, water, electricity, chemicals, labor, sanitary sewer and maintenance and repair.…”

“…The successful inactivation of a Creutzfeldt-Jajob disease (CDJ) agent (Taguchi et al, 1991), the inactivation of 22A strain of scrapie agent (Taylor et al, 1997), the prion decontamination (McDonnell et al, 2013;Murphy et al, 2009) and inactivation of potentially infectious agents including virus, bacteria, fungi and protozoa (Kaye et al, 1998;Murphy et al, 2007;Neyens et al, 2003;Dixon et al, 2012) have been proved.…”

Effects of alkaline hydrolysis and autoclaving on inorganic components present in healthcare waste

“…The complete inactivation of various microorganisms using alkaline hydrolysis has been proven in several studies (Taguchi et al 1991;Taylor et al 1997;Murphy et al 2009). This technology is used to destroy animal carcasses, tissues, anatomical parts, blood, body fluids, toxic agents and fixatives (Thacker and Leon 2004;Kalambura et al 2011).…”

High-Risk Biodegradable Waste Processing By Alkaline Hydrolysis

“…Alkaline hydrolysis ultimately degrades proteins by breaking chemical bonds (2). During hydrolysis, large protein molecules break into smaller (peptides), which is important for prion decontamination (13)(14)(15). All polypeptides contain carbon, hydrogen, nitrogen, and oxygen, with smaller proportions of other elements such sulphur and phosphorus.…”