Fate of Prions in Soil:  Adsorption and Extraction by Electroelution of Recombinant Ovine Prion Protein from Montmorillonite and Natural Soils

Abstract

Prions, the infectious agents thought to be responsible for transmissible spongiform encephalopathies, may contaminate soils and have been reported to persist there for years. We have studied the adsorption and desorption of a model recombinant prion protein on montmorillonite and natural soil samples in order to elucidate mechanisms of prion retention in soils. Clay minerals, such as montmorillonite, are known to be strong adsorbents for organic molecules, including proteins. Montmorillonite was found to have a large and selective adsorption capacity for both the normal and the aggregated prion protein. Adsorption occurred mainly via the N-terminal domain of the protein. Incubation with standard buffers and detergents did not desorb the full length protein from montmorillonite, emphasizing the largely irreversible trapping of prion protein by this soil constituent. An original electroelution method was developed to extract prion protein from both montmorillonite and natural soil samples, allowing quantification when coupled with rapid prion detection tests. This easy-to-perform method produced concentrated prion protein extracts and allowed detection of protein at levels as low as 0.2 ppb in natural soils.

Functional metaproteome analysis of protein extracts from contaminated soil and groundwater

“…There are basically two different strategies for protein extraction from soil. Whereas some groups used buffers containing salt and detergents to release proteins from the organic and inorganic components of the soil matrix (Rigou et al, 2006), others extracted proteins by dissolving the soil mineral matrix in concentrated HF (Schulze et al, 2005). Under more rigorous conditions more proteins are extracted, but also more contaminating humic compounds, which make further purification necessary.…”

Potential role of soil properties in the spread of CWD in western Canada

“…[14][15][16]19,[26][27][28] Prions have a strong affinity for clay minerals commonly found in soil; PrP Sc binds clay minerals (montmorillonite, Mte) avidly in comparison with quartz sand, an interaction that considerably enhances prion infectivity.…”

Prions in the environment

“…The N-domain has been shown to affect PrP aggregation, 92 and evidence suggests the N-domain might play a role in sorption to soils. 68,70,73,74,76 Therefore, both full-length and truncated prions should be used to study environmental fate.…”

“…74,75 An electroelution method developed by Rigou et al reported similar recoveries (5-40%). 73 It is likely that desorption selects for a certain PrP population, such as loosely-bound aggregates.…”