title: Circumventing tolerance to the prion protein (PrP): vaccination with PrP-displaying retrovirus particles induces humoral immune responses against the native form of cellular PrP.
abstract: Passive immunization with antibodies directed against the cellular form of the prion protein (PrPC) can protect against prion disease. However, active immunization with recombinant prion protein has so far failed to induce antibodies directed against native PrPC expressed on the cell surface. To develop an antiprion vaccine, a retroviral display system presenting either the full-length mouse PrP (PrP209) or the C-terminal 111 amino acids (PrP111) fused to the transmembrane domain of the platelet-derived growth factor receptor was established. Western blot analysis and immunogold electron microscopy of the retroviral display particles revealed successful incorporation of the fusion proteins into the particle membrane. Interestingly, retroviral particles displaying PrP111 (PrPD111 retroparticles) showed higher incorporation efficiencies than those displaying PrP209. Already 7 days after intravenous injection of PrPD111 retroparticles, PrPC-deficient mice (Prnp(o/o)) showed high immunoglobulin M (IgM) and IgG titers specifically binding the native PrPC molecule as expressed on the surface of T cells isolated from PrPC-overexpressing transgenic mice. More importantly, heterozygous Prnp(+/o) mice and also wild-type mice showed PrPC-specific IgM and IgG antibodies upon vaccination with PrPD111 retroparticles, albeit at considerably lower levels. Bacterially expressed recombinant PrP, in contrast, was unable to evoke IgG antibodies recognizing native PrPC in wild-type mice. Thus, our data show that PrP or parts thereof can be functionally displayed on retroviral particles and that immunization with PrP retroparticles may serve as a novel promising strategy for vaccination against transmissible spongiform encephalitis.
authors.affiliation: Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany.
authors.forename: Daphne
authors.initials: D
authors.lastname: Nikles
authors.forename: Patricia
authors.initials: P
authors.lastname: Bach
authors.forename: Klaus
authors.initials: K
authors.lastname: Boller
authors.forename: Christoph A
authors.initials: CA
authors.lastname: Merten
authors.forename: Fabio
authors.initials: F
authors.lastname: Montrasio
authors.forename: Frank L
authors.initials: FL
authors.lastname: Heppner
authors.forename: Adriano
authors.initials: A
authors.lastname: Aguzzi
authors.forename: Klaus
authors.initials: K
authors.lastname: Cichutek
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kalinke
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Buchholz
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D000906:Antibodies / Q000097:blood* / Q000276:immunology; D000937:Antigen-Antibody Reactions; D007108:Immune Tolerance; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D023421:Models, Animal; D018621:PrPC Proteins / Q000276:immunology*; D017096:Prion Diseases / Q000517:prevention & control; D011328:Prions / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology; D012190:Retroviridae / Q000235:genetics* / Q000378:metabolism; D014611:Vaccination
chemical_list: D000276:Adjuvants, Immunologic; D000906:Antibodies; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D018621:PrPC Proteins; D011328:Prions; D011993:Recombinant Fusion Proteins