Abstract

LCPs interact with ordered protein aggregates and sensitively detect amyloids of many different proteins, suggesting that they may possess antiprion properties. Here we show that a variety of anionic, cationic and zwitterionic LCPs reduced the infectivity of prion-containing brain homogenates and of prion-infected cerebellar organotypic cultured slices COCS, and decreased the amount of PrP(Sc) oligomers that could be captured in an avidity assay. Paradoxically, treatment enhanced the resistance of PrP(Sc) to proteolysis, and triggered the compaction and enhanced the resistance to proteolysis of recombinant mPrP(23-231) fibers. These results suggest that LCPs act as antiprion agents by transitioning PrP aggregates into structures with reduced frangibility. Moreover, ELISA on COCS and in vitro conversion assays with mPrP(23-231) indicated that PTAA may additionally interfere with the generation of PrP(Sc) by stabilizing the conformation of PrP(C) or of a transition intermediate. Therefore, LCPs represent a novel class of antiprion agents whose mode of action appears to rely on hyperstabilization, rather than destabilization, of PrP(Sc) deposits.