Conservation of infectivity in purified fibrillary extracts of scrapie-infected hamster brain after sequential enzymatic digestion or polyacrylamide gel electrophoresis.

Infectious extracts of scrapie-infected hamster brain enriched for scrapie-associated fibrils and scrapie amyloid protein (PrP) were partially denatured and subjected to either polyacrylamide gel electrophoresis with subsequent isolation of the PrP band or sequential enzymatic digestion with deglycosidase, phospholipase, proteinase, and several different nucleases. Infectivity measurements of these various specimens revealed a convincing association between infectivity and scrapie amyloid protein, with or without its sugar chains and disulfide bonds, and did not support the hypothesis that nucleic acid is involved in replication.