Inactivation of prion infectivity by ionizing rays

摘要

Inactivation of prion deposits on medical devices or prion contamination in pharmaceutical raw materials is considered as impossible by using gamma irradiation.Early,the guideline WHO/CDS/CSR/APH/2000 has described irradiation as an ineffective process.But,in 2003,S.Miekka et al.noted radiation inactivation of prions in a particular application to purify human albumin,shown by the physical denaturation of the infectious protein(PrP).The aim of our study was to determine the inactivation of prions with a scrapie model(strain C506M3)by irradiating standardised preparations.Results:Gamma irradiation was partially effective,showing a 4-5 log reduction on exposure to 50kGy.A characteristic effect-dose curve was not observed(25,50 and 100kGy),only an increase in the incubation period of the murine disease(229 days with 25kGy to 290 days with 100kGy)compared with 170 days without irradiation.Since the inactivation was not a total one,the observed effect is significant.It is proposed that further work be undertaken with the model to investigate the application of gamma radiation known levels of prion contamination.