Some physico-chemical parameters that influence proteinase K resistance and the infectivity of PrP Sc after high pressure treatment

Abstract

Crude brain homogenates of terminally diseased hamsters infected with the 263 K strain of scrapie (PrP Sc ) were heated and/or pressurized at 800 MPa at 60ºC for different times (a few seconds or 5, 30, 120 min) in phosphate-buffered saline (PBS) of different pH and concentration. Prion proteins were analyzed on immunoblots for their proteinase K (PK) resistance, and in hamster bioassays for their infectivity. Samples pressurized under initially neutral conditions and containing native PrP Sc were negative on immunoblots after PK treatment, and a 6-7 log reduction of infectious units per gram was found when the samples were pressurized in PBS of pH 7.4 for 2 h. A pressure-induced change in the protein conformation of native PrP Sc may lead to less PK resistant and less infectious prions. However, opposite results were obtained after pressurizing native infectious prions at slightly acidic pH and in PBS of higher concentration. In this case an extensive fraction of native PrP Sc remained PK resistant after pressure treatment, indicating a protective effect possibly due to induced aggregation of prion proteins in such buffers.

High pressure/temperature treatments to inactivate highly infectious prion subpopulations

“…Previous works have shown a strong reduction in the infectivity of scrapie prions as a function of pressure and heat (Fernandez Garcia et al, 2004;Heindl et al, 2005;Heindl, Fernandez Garcia, Butz, Pfaff & Tauscher, 2006) also associated to a decrease on the PK resistant fraction detected on immunoblots. Here the kinetic parameters governing the pressure inactivation of the 263K strain of scrapie were studied.…”

Degradation and destabilization of abnormal prion protein using alkaline detergents and proteases

“…Moreover, although some studies have shown that digestion with a protease in the presence of denaturing agents is sufficient to eliminate the infectivity of prion (22), others suggested a difference between the removal of immunoreactive material and infectivity (23)(24)(25)(26)(27). Alternatively, residual infectivity may be found in the portion of PrP Sc not recognized by SAF83.…”

Highlights of the 3rd International Conference on High Pressure Bioscience and Biotechnology

“…Prof. Bernhard Tauscher (Federal Research Center on Nutrition & Food, Karlsruhe, Germany) discussed results showing that food of high sensory quality and statistical sterility was produced by the combination of pressure and temperature, while most of the vitamins, peptides, food additives, metal ions, and compounds relevant for the sensory characteristics of food products were preserved. As an additional result, it was suggested that the effects of pressure on the prion protein might be an interesting methodology to prevent contamination by foodborne prion protein, since high hydrostatic pressure induces structural changes in the prion protein that make it susceptible to proteases (19).…”