EFFECT OF CHEMICALS, HEAT, AND HISTOPATHOLOGIC PROCESSING ON HIGH-INFECTIVITY HAMSTER-ADAPTED SCRAPIE VIRUS

High-titered (> 1010 LD50/g) preparations of scrapie virus-infected hamster brain were subjected to inactivation by various chemicals, autoclaving and histopathologic processing. Sodium hypochlorite, which reduced infectivity by .apprx. 4 log LD50/g of brain (99.99%), was somewhat superior to sodium metaperiodate and clearly superior to chlorine dioxide, Lysol I, potassium permanganate and H2O2. Most inactivation occurred within 15-30 min of exposure to a chemical, and little if any additional inactivation occurred after 1 h. Brains processed for histopathological examination (formalin fixation followed by dehydration in methanol, clearing in chloroform and embedding in paraffin) retained .gtoreq. 6.8 log LD50/g of the infectivity present in unprocessed control tissues (9.6 log LD50/g). Autoclaving at 121.degree. C for 1 h reduced the titer of scrapie virus by .apprx. 7.5 log LD50/g of brain but left 2.5 log LD50/g of residual infectivity. A combination of exposure to chemicals and autoclaving may be necessary to sterilize high-titered scrapie virus-infected tissue.