Partial copurification of scrapie-associated fibrils and scrapie infectivity.

The association between scrapie infectivity and scrapie-associated fibrils (SAF) during a partial purification procedure for infectivity was investigated. Scrapie infectivity and SAF can be separated from most membrane components by subcellular fractionation of infected mouse brain to obtain a synaptosomal fraction, followed by detergent treatment and density gradient centrifugation. After different detergent treatments, with either octyl glucoside or sodium N-lauroyl sarcosinate, SAF showed differing sedimentation characteristics but nevertheless cosedimented with scrapie infectivity in both cases. Copurification under two different conditions provides more evidence that SAF may be a form of the infectious agent of scrapie.