Characterization of four new monoclonal antibodies against the distal N-terminal region of PrP(c).

Prion diseases are a group of fatal neurodegenerative disorders that affect humans and animals. They are characterized by the accumulation in the central nervous system of a pathological form of the host-encoded prion protein (PrP(C)). The prion protein is a membrane glycoprotein that consists of two domains: a globular, structured C-terminus and an unstructured N-terminus. The N-terminal part of the protein is involved in different functions in both health and disease. In the present work we discuss the production and biochemical characterization of a panel of four monoclonal antibodies (mAbs) against the distal N-terminus of PrP(C) using a well-established methodology based on the immunization of Prnp (0/0) mice. Additionally, we show their ability to block prion (PrP(Sc)) replication at nanomolar concentrations in a cell culture model of prion infection. These mAbs represent a promising tool for prion diagnostics and for studying the physiological role of the N-terminal domain of PrP(C).

Identification of an epitope on the recombinant bovine PrP that is able to elicit a prominent immune response in wild-type mice.

The main cause for the development of transmissible spongiform encephalopathies (TSE) is the conformational change of prion protein from the normal cellular isoform (PrP(C)) into the abnormal isoform, named prion (PrP(Sc)). The two isoforms have the same primary structure, and with PrP being highly conserved among different species, no immune response to PrP(Sc) has been observed in infected humans or other mammals so far. The problem of inducing immune response was encountered when producing monoclonal antibodies against PrP, therefore mice lacking a functional Prnp gene were predominantly used for the immunization. In the present paper we report that by immunizing wild-type BALB/c mice with chemically unmodified recombinant bovine PrP a potent humoral immune response was achieved. Furthermore, we were able to isolate the monoclonal antibody (mAb) E12/2 and few other mAbs, all reacting specifically with bovine and human PrP, but not with PrP from several other mammals. The epitope of mAb E12/2 is located at the C-terminal end of helix 1, with His155 being crucial for binding. It has been proven that mAb E12/2 is useful for human and bovine TSE research as well as for diagnostics. Our results show that there are sufficient structural differences between mouse and bovine PrP to provoke a prominent humoral immune response.