Summary auto-generated
This study developed methods to detect PrPSc, the abnormal prion protein associated with transmissible spongiform encephalopathies (TSEs), in non-neural tissues. Researchers produced chicken antibodies against recombinant sheep prion protein and optimized immunoblotting procedures to sensitively detect PrPSc in tissue extracts. They examined spleen and brain samples from sheep with natural scrapie, experimentally infected sheep and goats, and cattle with bovine spongiform encephalopathy (BSE). PrPSc was readily detected in spleens of all naturally infected scrapie sheep and most experimentally infected sheep, particularly those challenged with the SSBP/1 scrapie strain. However, no PrPSc was detected in spleens from BSE-infected cattle despite being found in their brains. Results from some experimental TSE models also showed variable spleen PrPSc detection. The findings suggest that PrPSc deposition in peripheral organs depends on the infecting agent strain, host PrP genotype, and route of infection. The differential targeting of PrPSc between sheep scrapie and bovine BSE indicates these diseases may differ fundamentally in how they distribute throughout infected organisms, potentially limiting the diagnostic utility of splenic PrPSc detection for BSE.
Key findings
- PrPSc was consistently detected in spleens from all naturally scrapie-infected sheep and most experimentally infected sheep challenged with SSBP/1 strain
- No PrPSc was detected in spleens from BSE-infected cattle despite detection in brain tissue, indicating differential organ targeting between scrapie and BSE
- Detection of PrPSc in peripheral tissues depends on multiple factors including infecting agent strain, host PrP genotype, and route of infection
- The developed chicken antibody-based immunoblotting method achieved ~1000-fold concentration of PrPSc relative to normal PrP, enabling sensitive detection from tissue extracts
- Splenic PrPSc detection shows potential diagnostic value for sheep scrapie but not for BSE in cattle
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Abstract
The development of diagnostic tools for transmissible spongiform encephalopathies (TSEs) would greatly assist their study and may provide assistance in controlling the disease. The detection of an abnormal form of the host protein PrP in noncentral nervous system tissues may form the basis for diagnosis of TSEs. Using a new antibody reagent to PrP produced in chickens, PrP can be readily detected in crude tissue extracts. PrP from uninfected spleen had a lower molecular mass range than PrP from brain, suggesting a lower degree of glycosylation. A simple method for detecting the abnormal form of the protein, PrPSc, in ruminant brain and spleen has been developed. PrPSc was detected in sheep spleen extracts from a flock affected by natural scrapie and was also found in spleens from some, but not all, experimental TSE cases. In spleens from cattle with bovine spongiform encephalopathy (BSE) no PrPSc was detected. It is therefore suggested that there is differential targeting of PrPSc deposition between organs in these different types of TSE infection which, with other factors, depends on strain of infecting agent.