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Title: Conformation-dependent high-affinity mAbs to prion proteins

item Stanker, Larry
item SAFAR, JIRI - University Of California
item Hnasko, Robert

Submitted to: Journal of Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2010
Publication Date: 6/7/2010
Citation: Stanker, L.H., Serban, A.V., Safar, J., Hnasko, R.M., Prusiner, S.B. 2010. Conformation-dependent high-affinity mAbs to prion proteins. Journal of Immunology. 185:729-737.

Interpretive Summary: Bovine spongiform encephalopathy or BSE is a fatal neurological disease in cattle that was first described in the United Kingdom. The disease is caused by a prion or normal cellular protein that undergoes a change in shape resulting in the formation of large aggregates of the abnormal protein in the brain, cell death, and development for large vacuoles (spaces or holes) in the brain tissue. Conformation of the diagnosis of this disease currently is accomplished using immunoassays. Immunoassays rely on the ability of antibodies to specifically react with an antigen or pathogen, in this case binding to the prion protein in the brain. current tests, while able to detect abnormal protein are not sensitive and rely on the digestion of normal protein with enzymes. This research describes development of a highly sensitive monoclonal antibody that substantially increases detection sensitivity Incorporation of this antibody into prion diagnostics should provide producers and regulators with improved tools to identify and better manage BSE.

Technical Abstract: The prion diseases (or transmissible spongiform Encephalopathies) are fatal neurodegenerative illnesses caused by the accumulation of PrPSc, which is an alternatively folded isoform of the normal cellular prion protein (PrPC). These disorders are widespread and are found in humans (Creutzfeldt-Jkob disease), in sheep (scrapie), in elk and deer (chronic wasting disease), and in cattle (bovine spongiform encephalopathy) as well as in mink and cats. Detection of PrPSc commonly relies on immunochemical methods. In this study, we isolated monoclonal antibodies to bovine PrP that improved the performance of the Conformation-Dependent Immunoassay (CDI). The CDI is able to measure both the protease-resistant and -sensitive forms of PrPSc as well as PrPC. Following immunization of Prnp-null mice, a multitiered screening strategy was developed a panel of candidate antibodies. The characteristics and application of one of these monoclonal antibodies, F4-31 is described. Antibody binding to PrPC and PrPSC from different species, to reduced versus non-reduced PrP, to synthetic peptides, and to denatured PrP suggests that Mab 4-31 has a nonlinear, discontinuous epitope. Application of F4-31 as a capture reagent in the CDI substantially improved performance for detection of PrPSc in bovine brain.