Interaction Between A Model Prion Protein and Organo-Mineral Complexes

Infectious prion protein can persist in the environment for years and preserve their contagious capabilities. It was demonstrated that infectivity may persist in soil depending upon the different contributions by soil inorganic constituents. Nevertheless these findings provide only partial information because poor attention has been paid to the role of soil organic matter (OM). Here we point out the location and stability of a model prion protein (an ovine recombinant prion protein, recPrP), used as a simplified model of the natural cellular prion protein, upon its interaction with humic-like complexes via sorption or entrapment. Humic-like complexes were obtained by abiotic polymerization of catechol, a precursor of soil humic substances, through the reaction with birnessite, a manganese oxide. The protein- complexes were investigated by low temperature ashing (LTA) allowing the removal of OM layer by layer, thermal gravimetric and scanning electron microscopy analyses. The results seem to indicate that entrapped recPrP was less easily accessible to LTA treatment than sorbed recPrP. Therefore, we hypothesized that the processes leading to newly-formed organic matter can enhance prion stability in soil and thus potentially influence the environmental diffusion of infectivity. A comprehensive model of immobilization and protection in soils with different content and genesis of organic matter needs to be investigated.