Abstract
Extending the recent analysis of the safety of industrial bovine fat-derived products for human consumption (Müller, H., Stitz, L., and Riesner, D. (2006) Eur. J. Lip. Sci. Technol. 108, 812-826), we investigated systematically the effects of fat, fatty acids, and glycerol on the heat destruction of prions. Prion destruction was qualitatively and quantitatively evaluated in PrP 27-30, or prion rods, by the inactivation of infectivity as well as by the degradation of the polypeptide backbone. Under all conditions analyzed, inactivation of prion infectivity was achieved more efficiently than backbone degradation by several orders of magnitude. The presence of fat enhanced prion inactivation and offers a mild treatment for prion decontamination. In contrast, the presence of fat, fatty acids, and especially glycerol protected the PrP 27-30 backbone against heat-induced degradation. Glycerol also protected against heat-induced inactivation of prion infectivity. A phase distribution analysis demonstrated that prions migrated to the interphase of a fat/water mixture at room temperature and accumulated in the water phase at higher temperatures. In a systematic study of the mechanism of prion destruction, we found an intermediate structure of PrP that has fewer fibrils in beta-sheet formation, lower resistance to protease digestion, greater aggregation, and reduced solubility compared with PrP 27-30 but retains residual infectivity. These findings suggest that prion infectivity depends on beta-sheet-rich fibrillar structure and that inactivation proceeds in a stepwise manner, which explains the tailing effect frequently observed during inactivation.
Highlights
Deionized water Tallow Oleic acid Glycerol Highest temperature examined (Western blot/bioassay) Time to reach highest temperature (Western blot/bioassay)
Prion inactivation is less efficient in brain tissue compared with brain homogenate, which was suggested to be due to fat molecules protecting against heat inactivation [10]
Heat treatment of prion samples was performed in a lab-scale autoclave appropriate for high pressure [1], and analysis was accomplished by gel electrophoresis within amorphous aggregates, the Thioflavin T (ThT) assay is capable of dis- followed by Western blotting as well as by bioassays in Syrian criminating between amorphous and fibrillar structures
Summary
Deionized water Tallow Oleic acid Glycerol Highest temperature examined (Western blot/bioassay) Time to reach highest temperature (Western blot/bioassay). 27/28 min a In the presence of glycerol, a relative content as low as 2.5% tallow did not influence the degradation and inactivation experiments. The presence of large amounts of external lipids protects PrP 27–30 against heat degradation [20], which is of particular importance because the fat content of mammalian tissues and of brain is considerable. When milder, partially inactivating conditions are applied, a tailing phenomenon is observed [15, 21, 22] In this case, infectivity declines rapidly followed by slow inactivation with increasing treatment time. To establish a mechanistic model for heat destruction of prions, we provide qualitative and quantitative data on the inactivation of infectivity as well as the degradation of the PrP 27–30 polypeptide backbone under continuous variation of conditions, in the presence of different concentrations of fat, fatty acids, and glycerol
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
