Molecular hybridization studies with scrapie brain nucleic acids. I. Search for specific DNA sequences

Chromatography and hybridization techniques employing scrapie enriched fractions of hamster brains were employed to detect a scrapie-specific DNA molecule. 125I-labeled DNA from eight different scrapie-enriched hamster brain fractions was hybridized to total DNA and RNA from normal and scrapie hamster and mouse and to DNA from normal human brain and brain tissue from patients dying with Creutzfeldt-Jakob disease. Enrichment for infectivity was obtained by cellular partition, gel filtration and gel electrophoresis. Reassociation of the probes with the scrapie DNA did not have a higher value than with the normal. The level of detection in these studies indicated that if scrapie were a DNA virus replicating through DNA its specific infectivity would be lower than 687 molecules per infectious unit. These findings weaken the possibility that scrapie is a DNA virus.