Abstract: A monoclonal antibody which recognizes abnormal type prion protein alone is disclosed. By the present invention, an anti-abnormal type prion monoclonal antibody whose corresponding antigen is an abnormal type prion protein, and which does not substantially react with normal type prion protein was first provided. Since the corresponding antigen of the monoclonal antibody according to the present invention is the naturally occurring abnormal type prion protein, measurement of the abnormal type prion protein may be attained with high sensitivity.

Abstract: It is intended to provide a drug which is efficacious in treating a prion disease and has a high safety. A remedy for a prion disease which contains a mesenchymal stem cell as the active ingredient and a method of producing the same. A remedy for a prion disease which contains a mesenchymal stem cell, in particular, a mesenchymal stem cell having an anti-prion antibody gene transferred thereinto as the active ingredient and a method of producing the same. These remedies can not only prevent the progress of a prion disease but also contribute to the recovery of nerve dysfunction caused by the disease.