title: PrP antibody binding-induced epitope modulation evokes immunocooperativity.
abstract: We have characterized the antibody-antigen binding events of the prion protein (PrP) utilizing three new PrP-specific monoclonal antibodies (Mabs). The degree of immunoreactivity was dependent on the denaturation treatment with the combination of heat and SDS resulting in the highest levels of epitope accessibility and antibody binding. Interestingly however, this harsh denaturation treatment was not sufficient to completely and irreversibly abolish protein conformation. The Mabs differed in their PrP epitopes with Mab 08-1/11F12 binding in the region of PrP(93-122), Mab 08-1/8E9 reacting to PrP(155-200) and Mab 08-1/5D6 directed to an undefined conformational epitope. Using normal and infected brains from hamsters, sheep and deer, we demonstrate that the binding of PrP to one Mab triggers PrP epitope unmasking, which enhances the binding of a second Mab. This phenomenon, termed positive immunocooperativity, is specific regarding epitope and the sequence of binding events. Positive immunocooperativity will likely increase immunoassay sensitivity since assay conditions for PrP(Sc) detection does not require protease digestion.
authors.affiliation: Department of Biochemistry, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, USA.
authors.forename: Binggong
authors.initials: B
authors.lastname: Chang
authors.forename: Michael W
authors.initials: MW
authors.lastname: Miller
authors.forename: Marie S
authors.initials: MS
authors.lastname: Bulgin
authors.forename: Sharon
authors.initials: S
authors.lastname: Sorenson-Melson
authors.forename: Aru
authors.initials: A
authors.lastname: Balachandran
authors.forename: Allen
authors.initials: A
authors.lastname: Chiu
authors.forename: Richard
authors.initials: R
authors.lastname: Rubenstein
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000937:Antigen-Antibody Reactions; D019921:Biotinylation / Q000379:methods; D015153:Blotting, Western; D001921:Brain / Q000473:pathology; D006224:Cricetinae; D003670:Deer; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D000939:Epitopes / Q000276:immunology*; D018621:PrPC Proteins / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D012608:Scrapie / Q000276:immunology* / Q000473:pathology; D012756:Sheep; D034081:Wasting Disease, Chronic / Q000276:immunology* / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D018621:PrPC Proteins