Chemical Inactivation of Prions Is Altered by Binding to the Soil Mineral Montmorillonite

Abstract

Environmental routes of transmission contribute to the spread of the prion diseases chronic wasting disease of deer and elk and scrapie of sheep and goats. Prions can persist in soils and other environmental matrices and remain infectious for years. Prions bind avidly to the common soil mineral montmorillonite, and such binding can dramatically increase oral disease transmission. Decontamination of soil in captive facilities and natural habitats requires inactivation agents that are effective when prions are bound to soil microparticles. Here, we investigate the inactivation of free and montmorillonite-bound prions with sodium hydroxide, acidic pH, Environ LpH, and sodium hypochlorite. Immunoblotting and bioassays confirm that sodium hydroxide and sodium hypochlorite are effective for prion deactivation, although montmorillonite appears to reduce the efficacy of hypochlorite. Acidic conditions slightly reduce prion infectivity, and the acidic phenolic disinfectant Environ LpH produces slight reductions in infectivity and immunoreactivity. The extent to which the association with montmorillonite protects prions from chemical inactivation appears influenced by the effect of chemical agents on the clay structure and surface pH. When clay morphology remains relatively unaltered, as when exposed to hypochlorite, montmorillonite-bound prions appear to be protected from inactivation. In contrast, when the clay structure is substantially transformed, as when exposed to high concentrations of sodium hydroxide, the attachment to montmorillonite does not slow degradation. A reduction in surface pH appears to cause slight disruptions in clay structure, which enhances degradation under these conditions. We expect our findings will aid the development of remediation approaches for successful decontamination of prion-contaminated sites.

Movement of Chronic Wasting Disease Prions in Prairie, Boreal and Alpine Soils

“…Therefore, to predict the fate of prions in soils, it is important to analyze soil properties [ 36 ]. Prion persistence in soil is a dynamic balance between protective microenvironments, such as binding to minerals, which favor prion stability [ 37 , 38 ] versus processes leading to their degradation.…”

Predicting chronic wasting disease in white-tailed deer at the county scale using machine learning

“…Afterall, the other three candidate algorithms performed similarly with these data (see Table S2 in the Supplement), and their results hinged on entirely different sets and ranks of factor importances. Specifically, the RF algorithm ranked hunter harvest (a proxy for deer density) 36 , clay-based soils 37 – 41 , forest cover 13 , and then distance to streams 35 as the most important features driving its predictions of CWD-status, in that order. The DT algorithm ranked hunter harvest 36 , distance to streams 35 , clay-based soils 37 – 41 and then forest cover 13 as the top features of importance driving its predictions of CWD-status, in that order.…”

“…Specifically, the RF algorithm ranked hunter harvest (a proxy for deer density) 36 , clay-based soils 37 – 41 , forest cover 13 , and then distance to streams 35 as the most important features driving its predictions of CWD-status, in that order. The DT algorithm ranked hunter harvest 36 , distance to streams 35 , clay-based soils 37 – 41 and then forest cover 13 as the top features of importance driving its predictions of CWD-status, in that order. And finally, the GB algorithm ranked hunter harvest 36 , distance to streams 35 , forest cover 13 , and then clay-based soils 37 – 41 as the top features driving its predictions of CWD-status, in that order.…”

Improved predictions and forecasts of chronic wasting disease occurrence using multiple mechanism dynamic occupancy modeling

“…Chronic wasting disease persistence was negatively correlated with clay soil constituents, a relationship previously identified in northern Illinois, USA (Dorak et al 2017). Kuznetsova et al (2020) reported that prions readily bind to clay particles and become increasingly more difficult to extract over time but remain infectious, and others have indicated that clay‐bound prions increase the transmissibility of CWD (Booth et al 2021). Based on these relationships, we might expect that increasing clay content would result in a higher likelihood of CWD persistence, but this was not supported by our study or Dorak et al (2017).…”