| Prions are proteinaceous particles recognized as the infectious agent of transmissible spongiform encephalopathies (TSEs). Prions are believed to be predominately, if not entirely composed of PrPTSE, a beta-sheet rich isoform of cellular prion protein (PrPC).;There is evidence that the soil environment may serve as a reservoir of prion infectivity and contribute to the transmission of sheep scrapie and cervid chronic wasting disease. Prions are known to be persistent in the environment and unusually resistant to most conventional pathogen inactivation treatments. There is evidence that prions adsorb strongly to soil particles, resist desorption, and enhance oral disease transmission relative to unbound agent.;Attachment to mineral surfaces may protect prions from inactivation in the soil environment or the digestive system, and contribute to their persistence in contaminated environments. Here, we examine both abiotic and biotic degradation of prions in the presence and absence of the soil mineral, montmorillonite. Our results indicate that the oxidant, peroxymonosulfate (PMS) is capable of rapid degradation of at least two strains of disease-associated prion protein, and transition metal activation of PMS to produce reactive oxygen species appears to enhance degradation. Liquid chromatography/tandem mass spectrometry data revealed that PMS exposure results in a methionine - targeted oxidative modification to PrPTSE. We also found that the extent to which attachment to Mte protects prions from chemical inactivation is governed by the effect of the chemical on the overall clay structure and surface acidity. When clay morphology is relatively unaltered, Mte-bound prions appear to be protected from sodium hypochlorite inactivation. However, when clay structure is substantially transformed, prion attachment to Mte does not slow hydrolysis by sodium hydroxide. Exposure of Mte to acidic conditions actually appears to enhance degradation of attached prions, a phenomenon that may be driven by an increase in surface acidity at low pH. Lastly, we have data indicating that enzymes extracted from bovine manure compost are capable of misfolded prion protein degradation, and breakdown of PrPTSE occurs in less than 24 hours at temperatures less than or equal to 55 °C. Together, our research helps frame expectations about prion inactivation in the environment. |
