Transmission of scrapie by steel-surface-bound prions

Background: Prions are unusually resistant to conventional disinfection pro cedures. An electrode used intracerebrally on a Creutzfeldt-Jakob disease ( CJD) patient transmitted the disease to two patients in succession and fina lly to a chimpanzee, despite attempted disinfection. Concerns that surgical instruments may transmit variant CJD have been raised by the finding of Pr PSc, a surrogate marker for infectivity, in various tissues other than brai n. Materials and Methods: Stainless steel wire was exposed to scrapie-infected brain or brain homogenate, washed exhaustively and inserted into the brain of indicator mice to measure infectivity. Results: A contact time of 5 min with scrapie-infected mouse brain suffices to render steel wire highly infectious and insertion of infectious wire in to the brain of an indicator mouse for 30 min suffices to cause disease. in fectivity bound to wires persists far longer in the brain than when injecte d as homogenate, which can explain the extraordinary efficiency of wire-med iated infection. No detectable amounts of PrP could be eluted with NaOH, ho wever the presence of PrP on infectious wires was demonstrated by chemilumi nescence. Several recommended sterilisation procedures inactivated wire-bou nd mouse prions, but exposure to 10% formaldehyde was insufficient. Conclusions: Prions are readily and tightly bound to stainless steel surfac es and can transmit scrapie to recipient mice after short exposure times. T his system mimics contaminated surgical instruments and will allow an asses sment of sterilisation procedures.