Characterization of BSE and scrapie strains/isolates

Following the BSE epidemic in cattle and the emergence of a variant form of Creutzfeldt-Jakob disease in humans, the question was raised whether BSE h as been transmitted to small ruminants by the inadvertent feeding of infect ious meat and bone meal. Such infections could easily be conceiled in count ries where scrapie is endemic. To address this issue by immune-chemically a nalyzing the PrPSc fragments, we have developed two lines of research. Firs tly we have focused on the development of criteria for the differential cha racterization of experimental BSE and scrapie strains/isolates in rodents. To date, three criteria have been identified: quantification of the relativ e banding intensities of PrPSc glycotypes using a photoimaging technique; t he non-uniform kinetic of proteinase K degradation of PrPSc; and difference s in the molecular masses of their nonglycosylated PrPSc fragments after PK cleavage in immunoblot. The second line of research focused on the impleme ntation of the criteria described above to representative samples from scra pie diseased Irish sheep. Using these three criteria, no evidence was found for the presence of a BSE infection in these animals. However, the final c onclusion must take into account the results of mouse incubation lime and m ouse lesion profile data which are currently being generated.