Scrapie-associated tubulofilamentous particles in human Creutzfeldt-Jakob disease.

Scrapie-associated fibrils (SAF) were demonstrated by a simple negative staining method for electron microscopy from fresh and frozen brains with naturally occurring human Creutzfeldt-Jakob disease (CJD). The findings confirm that SAF occur as an internal part of a larger three-layer particle. The two outer coats of SAF can be disrupted by detergent alone or can be digested in two stages by a combination of proteolytic enzymes and subsequent treatment with DNase and mung bean nuclease. Examination of thin sections from the cerebral cortex of brains from patients with CJD revealed the presence of 26-30-nm diameter tubulofilamentous particles, identical to those previously described in natural scrapie of sheep and bovine spongiform encephalopathy and also in experimentally induced scrapie in mice and hamsters and CJD-infected mice and chimpanzees. Thus, it would appear that the particles are not contaminants passaged in experimental animals.