Effects of Solution Chemistry and Aging Time on Prion Protein Adsorption and Replication of Soil-Bound Prions

Abstract

Prion interactions with soil may play an important role in the transmission of chronic wasting disease (CWD) and scrapie. Prions are known to bind to a wide range of soil surfaces, but the effects of adsorption solution chemistry and long-term soil binding on prion fate and transmission risk are unknown. We investigated HY TME prion protein (PrPSc) adsorption to soil minerals in aqueous solutions of phosphate buffered saline (PBS), sodium chloride, calcium chloride, and deionized water using western blotting. The replication efficiency of bound prions following adsorption in these solutions was also evaluated by protein misfolding cyclic amplification (PMCA). Aging studies investigated PrPSc desorption and replication efficiency up to one year following adsorption in PBS or DI water. Results indicate that adsorption solution chemistry can affect subsequent prion replication or desorption ability, especially after incubation periods of 30 d or longer. Observed effects were minor over the short-term (7 d or less). Results of long-term aging experiments demonstrate that unbound prions or prions bound to a diverse range of soil surfaces can readily replicate after one year. Our results suggest that while prion-soil interactions can vary with solution chemistry, prions bound to soil could remain a risk for transmitting prion diseases after months in the environment.

Humic substances interfere with detection of pathogenic prion protein

“…NOM or NOM surrogates appear to enhance a-recPrP binding to soil particles (Polano et al, 2008;Pucci et al, 2008;Rao et al, 2007). While recent studies have examined enzymatic digestion (Saunders et al, 2010;Saunders et al, 2011b) and in vitro replication (Saunders et al, 2011c) of bona fide PrP TSE bound to humic acid-coated SiO 2 microparticles (Saunders et al, 2010(Saunders et al, , 2011b interacts with at least some NOM components (e.g., polyphenolic structures) and that NOM can modulate prion disease progression (at least by the intracerebral route of exposure). Complexation with humic substances has been suggested to enhance protein persistence in soils (Hsu and Hatcher, 2005;Zang et al, 2000), and may contribute to the preservation of prions in soil environments.…”

Prions: the danger of biochemical weapons

“…The evidence that soil and other environmental surfaces can play a role as reservoir of Prions dissemination contributes to the imminent threat these particles can represent if they are released into the environment Saunders et al, 2011b). Finally, the impact that Prions could cause to wildlife, especially mammals, is terrifying; people who had been in contact to contaminated environments or had ingested inoculated animals could die in days, months, or years.…”

Intranasal Inoculation of White-Tailed Deer (Odocoileus virginianus) with Lyophilized Chronic Wasting Disease Prion Particulate Complexed to Montmorillonite Clay

“…After contaminated urine, feces or saliva have been deposited in the environment on forage and soil, they become available for ingestion and inhalation. Soil particles, particularly clay, tightly adsorb prions [9], [11], [12] and soil is inadvertently ingested during foraging with deer consuming an average of 16 g of soil per day [13]. Soil is also intentionally ingested at mineral licks, which are utilized by deer, elk and moose (our unpublished observations).…”