Involvement of protein in scrapie agent infectivity

Fate of prions in soil: a review

Prions are the etiological agents of transmissible spongiform encephalopathies (TSSEs), a class of fatal neurodegenerative diseases affecting humans and other mammals. The pathogenic prion protein is a misfolded form of the host-encoded prion protein and represents the predominant, if not sole, component of the infectious agent. Environmental routes of TSE transmission areimplicated in epizootics of sheep scrapie and chronic wasting disease (CWD) of deer, elk, and moose. Soil represents a plausible environmental reservoir of scrapie and CWD agents, which can persist in the environment for years. Attachment to soil particles likely influences the persistence and infectivity of prions in the environment. Effective methods to inactivate TSE agents in soil are currently lacking, and the effects of natural degradation mechanisms on TSE infectivity are largely unknown. An improved understanding of the processes affecting the mobility, persistence, and bioaviailability of prions in soil is needed for the management of TSE-contaminated environments.

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.

Infectious scrapie agent is apparently not as small as recent claims suggest

A potentially important claim that the minimum size of infectious scrapie agent is 50,000 Mr or less has been investigated. Our results suggest that the agent is larger and that the original experiment was misinterpreted.