Sodium hydroxide renders the prion protein PrPSc sensitive to proteinase K

Sodium hydroxide (NaOH) solutions are widely used for the purification of contaminated equipment, as they are known to inactivate a variety of pathogens. However, information about their effect on agents causing transmissible spongiform encephalopathy (TSE) is sparse and contradictory. Scrapie hamster brain homogenate, containing the disease-associated form of the prion protein (PrP^Sc), was exposed to NaOH. Kinetics studies showed that treatment of brain homogenate with millimolar concentrations of NaOH rapidly abolished the proteinase K-resistant form of the prion protein (PrP^res). NaOH treatment converted PrP^Sc into a protease-sensitive form, either in solution or when adsorbed to a metallic surface. If infectivity of TSEs is linked with PrP^res, the results imply that inactivation of TSE occurs more efficiently than currently assumed.