MAPPING THE PRION PROTEIN USING RECOMBINANT ANTIBODIES

The fundamental event in prion disease is thought to be the posttransl ational conversion of the cellular prion protein (PrPC) into a pathoge nic isoform (PrPSc). The occurrence of PrPC on the cell surface and Pr PSc in amyloid plaques in situ or in aggregates following purification complicates the study of the molecular events that underlie the disea se process, Monoclonal antibodies are highly sensitive probes of prote in conformation which can be used under these conditions, Here, we rep ort the rescue of a diverse panel of 19 PrP-specific recombinant monoc lonal antibodies from phage display libraries prepared from PrP defici ent (Prnp(o/o)) mice immunized with infectious prions either in the fo rm of rods or PrP 27-30 dispersed into liposomes. The antibodies recog nize a number of distinct linear and discontinuous epitopes that are p resented to a varying degree on different PrP preparations. The epitop e reactivity of the recombinant PrP(90-231) molecule,vas almost indist inguishable from that of PrPC on the cell surface, validating the impo rtance of detailed structural studies on the recombinant molecule. Onl y one epitope region at the C terminus of PrP was well presented on bo th PrPC and PrPSc, while epitopes associated with most of the antibodi es in the panel were present on PrPC but absent from PrPSc.