Figure 1

Stability of BSE isolates. (A). Western blot of isolates passaged in cattle. Obex samples were characterized by PK- western blotting (mAb 6H4). Lanes from left: 1, Biotinylated protein marker; 2, Bovine TME (Animal #14, 0.5 mg); 3, Canadian L-type (#11, 0.5 mg); 4, French L-type (#8, 1 mg); 5, BASE (#10, 0.5 mg); 6, U.S. H-type (#7, 1 mg); 7, French H-type (#5, 1 mg); 8, Classical (#4, 1 mg); 9, Marker. Molecular weights of ladder bands were: *, 31 kDa; **, 21 kDa. (B-D). Curves represent the average of biological replicates except where noted with 3 to 5 technical replicates per animal. The same stock of GdnHCl was used for curves that were directly compared. Error bars reflect standard error of the mean (SEM), except where indicated. (B). Comparison of TSEs from natural hosts. Curves represent the average of 2-3 experiments from a representative animal; error bars represent standard deviation. Open triangles—Classical BSE (Animal #3); Closed circles—136-VDEP sheep scrapie [14]; Closed squares—U.S. elk CWD [34]. Inset: Comparison of U.S. scrapie isolates 136-VDEP (closed circles) and 13-7 (open circles). (Absolute [GdnHCl]1/2 values differ here due to differences in experimental conditions). (C). Classical vs. L-type BSE. The L-type overall curve (closed squares) is averaged across 4 biological replicates, and the classical curve (closed circles) is the average of 3 biological replicates, using the standard method. The French L-type curve (open triangles) is the average of 2 samples and the BASE (open circles) and Canadian L-type (closed triangles) curves represent individual biological replicates. Inset: Classical (closed circles) and Overall L-type (open circles) curves are displayed separately for ease of viewing. (D). Classical vs. H-type BSE. Curves represent averages of 3 biological replicates of each performed using the buffered method. Closed circles—Classical BSE; Open circles—H-type BSE.