Distinct immunohistochemical localization in Kuru plaques using novel anti-prion protein antibodies.

By immunizing Prnp-knockout mice with synthetic polypeptides, a panel of mAbs directed to bovine PrP C was obtained. ThemAb panel was characterized by the ELISA method, where synthetic polypeptides were used for epitope mapping. Different reactivity patterns were identified. The ability of these mAbs to detect abnormal PrP Sc in CJD cases was studied by immunohistochemistry. All mAbs were tested for PrP Sc in murine, bovine, monkey and human brain tissues. Three mAbs recognized the fragmented PrP epitope in our ELISA. Antibody 1D12 was strongly reactive to ovine and squirrel monkey tissues infected with a scrapie agent, although non-reactive to scrapie-infected mouse tissues. Antibody 2D8 was clearly reactive to type-2 but not type-1 CJD human tissues. Of particular interest was the reactivity of mAb 6C4 with the inner structure of Kuru plaques (peripheral pattern) in a type-2 CJD case and mAb T2, 1D12, 2B11, 2D8, 4B5 and 6G32 with the central area (central pattern). The fact that different anti-PrP mAbs possess distinct staining properties suggests that the PrP C to PrP Sc conversion might involve amultiple-step process.