Prions, are proteinaceous particles recognized as the agents of a class of neurodegenerative disorders, called transmissible spongiform
encephalopathies (TSE), or prion diseases. Epidemiological data suggest that TSE-contaminated environments may serve as source of
infectivity, but there is no information about adsorption of prions onto soil. We carried out experiments by mixing, healthy, or scrapieinfected hamster brains homogenates with three types of soil suspended in different buffers: (i) two saline buffers, i.e., phosphate buffer
solution (PBS) and CaCl2
solution; (ii) a mix of nondenaturing detergents, i.e., Triton X-100 and sodium deoxycholate (DOC) solution;
(iii) a non-ionic detergent, i.e., lauryl maltoside; (iv) two anionic detergents, i.e., Sarkosyl or sodium dodecyl sulphate (SDS); and (v) a
chaotropic agent, i.e., urea. The unbound prion proteins were detected in the supernatants (after centrifugation of soil suspension) by
Western blotting. Results clearly demonstrate that both the no infectious (PrP
C
) and infectious (PrP
Sc
) forms are adsorbed by all soils.
Only 1% sodium dodecylsulphate (SDS) partially impeded the association of PrP
C
, but not that of PrP
Sc
with the sandy loam soil.
Agents with different interacting properties towards hydrophilic and/or hydrophobic domains failed to extract PrP
Sc
from sediments of
soil–brain homogenate mixtures. The strong interaction of PrP
Sc
with soil favors the accumulation of prions in soils, especially if
amended with prion-containing organic fertilizers and/or whenever TSE-affected animal carcasses, placenta, and excreta in general are
buried or laid at the soil surface.
