Chemical inactivation of prion

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Prion decontamination requires very harsh treatment such as soaking in concentrated sodium hydroxide, sodium hypochlorite or autoclaving at 134℃ to eliminate all infectivity. However, as Iong as the daily disinfection of medical equipment is concerned, the infectivity titer of the contaminated materials is relatively low. Therefore, a mild decontamination procedure would be adequate so that contaminated materials are not damaged by severe chemical or physical treatments. Liquid ethylene oxide (LEO) was found to cause a dose-dependent decrease in prion infectivity in 1% scrapie-mouse brain homogenates, and the reduction attained by treatment with 2% LEO at 25℃ for 40 h reached more than 10^<-5>. LEO is, however, difficult to handle and takes relatively long time to inactive prion. Therefore, we screened three epoxides, β-propiolactone, propylene oxide, and glycidol (GLD), which resemble to EO in their structures but are easier in handling than LEO.Among these chemicals, GLD worked most effectively and degraded prion protein into small fragments. As a result of the bioassay, treatment with 3% GLD for 5 hr and 5% GLD for 2, 5 hr or 12 hr at room temperature prolonged the mean incubation time by 44, 30, 110 and 73 days, respectively. From dose-incubation time standard curve, the decrease in infectivity titers was estimated as 10a^<-3> or more. Therefore, degradation of prion protein by GLD decreased the scrapie infectivity. Effect of GLD was enhanced by high pH around 8 and presence of some salt such as 0.15 M NaCl together with higher temperature of 50℃. However, the mouse-bioassay are not available at present.