Figure 2. Hamster scrapie prions (PrP^HY) bind to mineral fractions of soils S1 and S2. Identical amounts of 10% brain homogenate (BH^HY) were incubated with soils overnight at room temperature. Samples were fractionated through a sucrose cushion to separate bound PrP^HY from unbound; both pellet (bound PrP^HY) and supernatant (unbound PrP^HY) were analyzed for presence of PK-resistant PrP^HY by western blot with 3F4 antibody. Soil S1 with clay texture and montmorillonite-kaolinite mineralogical composition binds more PrP^HY compared with soil S2 with sandy-loam texture and Illite-kaolinite composition.