Development of an Enzymatic Detergent Treatment Protocol That Significantly Reduces Protease Resistant Prion Protein Load and Infectivity from Prion-Contaminated Surgical-Steel Monofilaments

BACKGROUND/OBJECTIVES: The unconventional nature of the infectious agent of prion diseases poses a challenge to conventional infection control methodologies. In this study PrPSc was used as a biochemical marker of prion infectivity to identify enzymatic detergent preparations and conditions that could be used to degrade PrPSc present in homogenate and surface bound preparations of prion-infected brain tissue. METHODS: The ability of four enzymatic detergent preparations including new formulations of 3M™ Rapid Multi-Enzyme Cleaner (RMEC) trial formulation A and trial formulation B; Ruhof Endozime AW Plus; Steris Klenzyme, to degrade PrPSc associated with prion-infected mouse brain homogenates and prion-contaminated surgical-steel wires was analysed using a high sensitivity, quantitative western blot method. Prion infectivity was determined by mice bioassay of prion-contaminated surgical-steel wires. RESULTS: All products tested failed to completely degrade PrPSc under conditions experienced in automated washing systems. Further optimisation of RMEC trial formulation A and RMEC trial formulation B indicated that an extended treatment time (30 minutes) and higher temperatures (50-60°C) decreased detectable levels of PrPSc from prion-infected brain homogenates by more than 2 logs and completely removed detectable levels of PrPSc from prion-contaminated surgical-steel monofilaments. Bioassay indicated that incubation period was extended when wires were treated under optimised conditions with RMEC trial formulation A and trial formulation B versus wires treated with 1N NaOH. CONCLUSIONS: Optimisation of treatment protocols indicates that with extended treatment times and higher temperatures enzymatic detergents can be used to reduce the PrPSc load and prion infectivity from surgical-steel instruments. Direct research support provided by a commercial organization. 3M