Synthetic peptide vaccines yield monoclonal antibodies to cellular and pathological prion proteins of ruminants

S Harmeyer, E Pfaff and MH Groschup Federal Research Centre for Virus Diseases of Animals, Tubingen, Germany. Transmissible spongiform encephalopathies are closely linked to the accumulation of a pathological isoform of a host-encoded prion protein (PrP(C)), designated PrP(Sc). In an attempt to generate mono- and polyclonal antibodies to ruminant PrP, 32 mice were vaccinated with peptide vaccines which were synthesized according to the amino acid sequence of ovine PrP. By this approach five PrP-reactive polyclonal antisera directed against four different domains of the protein were stimulated. Splenocytes of mice which had developed PrP-reactive antibodies were used for the generation of monoclonal antibodies (MAbs). Obtained PrP-specific MAbs were directed to three different domains of ruminant PrP which differed from the three previously described major MAb binding sites in rodent PrP. MAbs exhibited reactivity with non-denatured ruminant PrP(C) in ELISA and immunoprecipitation and with denatured ovine and bovine PrP(Sc) in immunoblot. Cross-reactivity was observed with PrP(C) of nine other mammalian species and with pathological PrP preferably of ruminants and weakly with that of hamster and mouse. The generated MAbs will be useful tools for the development of diagnostic tests for BSE and scrapie as well as for pathogenesis studies of these diseases.