Fig. 2.

Biochemical characterization of PrP^Sc associated with discordant sheep isolates. (A) Comparative PK digestion assay performed on brain material from tg338 mice infected with one of the following isolates: conventional scrapie [PG127 (25)], discordant (DS2), or Nor98 Rauland (see Tables 1 and 2). The homogenates were treated for 10 min at 37°C with PK at the indicated concentrations and analyzed by Western blotting. (B) Atypical Nor98-like PrP^res profiles observed in the brain material from discordant sheep (DS2 and DS8). PrP^Sc prepared by NaPTA precipitation was subjected (+)ornot (-) to mild PK digestion (37). Note the lack of PrP^res signal in PK-treated brain material from a healthy sheep (NI) and the typical profile of PrP^res detected in brain material from a conventional scrapie-diseased sheep [Langlade (25)]. (C) Similarity of the PrP^res patterns observed in brain materials from the donor (ARR/ARR sheep DS8) and from tg338 recipient mice.