A two-step processing method is recommended to inactivate human sporadic M1 and V2 prions

Most human-acquired prion diseases result from infection with M1 or V2 prions from sporadic Creutzfeldt–Jakob disease. To prevent transmission via surgical instruments, sterilization methods targeting these prions are essential. In this study, stainless steel wires coated with M1 or V2 prions were used to evaluate inactivation protocols. None of the individual treatments – autoclaving, SDS or NaOH – eliminated infectivity except for autoclaving against V2 prions. Autoclaving at 134 °C revealed distinct thermal stability between M1 and V2, with M1 exhibiting greater thermal stability. Importantly, combining methods, which we herein called two-step processing methods, achieved practical inactivation: SDS treatment followed by autoclaving at 121 °C was highly effective. Commercial alkaline detergents also proved effective against M1 prion under a combination of high pH and temperature. The inability to detect infection in our model mice using our assay system demonstrates that the infectivity titre decreased to 10⁻⁸ in M1 and 10⁻⁷ in V2. These findings indicate that synergistic approaches can achieve prion inactivation under practical conditions, supporting the need for revised sterilization protocols to prevent iatrogenic transmission.