Applicability of three anti-PrP peptide sera including staining of tonsilsand brainstem of sheep with scrapie

Three rabbit antibodies (R521, R505, R524) were produced, and raised to syn thetic peptides corresponding to residues 94-105, 100-111, and 223-234, res pectively, of the sheep prion protein (PrP). Epitope mapping analysis revea led the monospecific character of antisera R505 and R524. In addition to th e amino acid sequence against which it was raised, R521 also recognized oth er small epitopes. ELISA and radio-immunoprecipitation were used to assess the relative immunoreactivities of the antisera to the normal sheep prion p rotein (PrPc). Highest reactivity was found for R521, followed by R505 and R524. According to Western blot analysis, all three sera specifically react ed with the prion proteins PrPSc and PrP27-30, extracted from the brain ste m of a scrapie-affected sheep. Yet, with R505 not all of the lower molecula r weight deglycosylated forms could be detected. Contrary to the immunoreac tivities found with the PrPSc and PrP27-30 isoforms, only R521 recognised P rPc from a healthy sheep. The usefulness of all three anti-peptide sera in the immunohistochemical detection of PrPSc in brain stem and tonsils of scr apie-affected sheep was demonstrated and compared with an established rabbi t anti-PrP serum. (C) 2000 Wiley-Liss, Inc.