Western blots of PrP in brains from Tg mice inoculated with BSE prions and cattle with BSE. Each undigested control aliquot (− lanes) contained approximately 5 μg of total protein; aliquots digested with proteinase K (+ lanes) consisted of the equivalent of 25 μg of undigested, total protein. Samples in lane pairs: 1, bovine medulla from case PG31/90; 2, Tg(BoPrP)4092/Prnp0/0, uninoculated; 3, Tg(BoPrP)4092/Prnp0/0 clinically ill after inoculation with case PG31/90; 4, Tg(BoPrP)4092/Prnp0/0 clinically ill after inoculation with case GJ248/85; 5, Tg(BoPrP)4125/Prnp0/0, uninoculated; 6, Tg(BoPrP)4125/Prnp0/0 clinically ill after inoculation with case PG31/90; 7, Tg(BoPrP)4125/Prnp0/0 clinically ill after inoculation with case GJ248/85; 8, Tg(BoPrP)333 clinically ill after inoculation with PG31/90 prions; 9, Tg(BoPrP)333 clinically ill at approximately 500 days after inoculation with the sheep scrapie SSBP/1 isolate.