FIGURE 1.

Efficient recombinant prion propagation by PMSA using different prion-coated beads as seed. Electrophoresis and total protein staining of the PMSA products obtained, using either 1 or 5 recombinant prion-coated beads of different materials as seeds, showing rec-PrP^res after treatment with Proteinase K (PK). Prion-coated beads of glass, zirconia/silica, stainless steel and Teflon^® were used as seeds and the same beads without prion coating were also submitted to the same process as controls of cross-contamination or spontaneous rec-PrP^res formation. Unseeded (Uns.) reactions without beads and without any seeding were also used for this purpose. All prion-coated beads were able to give rise to rec-PrP^res, showing the same electrophoretic patterns as the original Sst01 strain with predominant ∼16 and ∼9 kDa fragments. No cross-contamination or spontaneous formation of rec-PrP^res was detected in any of the unseeded reactions either with or without beads. A sample of the substrate rec-PrP without PK digestion is also shown as reference for the size of the undigested rec-PrP. MW, Molecular weight marker.