Chicken antibody against a restrictive epitope of prion protein distinguishes normal and abnormal prion proteins

Recently, we reported the application of a recombinant chicken IgY monoclonal antibody, Ab3–15, against mammalian prion protein (PrP), for the diagnosis of bovine spongiform encephalopathy in cattle. In this study, we have characterized a soluble, single-chain variable fragment (scFv) form of this antibody, sphAb3–15 using brain homogenates from mice. This sphAb3–15 antibody recognized denatured forms of both PrP C and PrP Sc, and PrP Sc after PK-treatment, on Western blotting. In sandwich ELISAs, on dot blots and by immunoprecipitation, sphAb3–15 efficiently bound to PrP from normal brain homogenates, but weakly bound PrP from scrapie-infected brain homogenates. These results suggest that sphAb3–15 selectively recognizes PrP C under native conditions and that the epitope recognized by sphAb3–15 may undergo conformational changes during the conversion of PrP C into PrP Sc.