University of Tras-os-Montes and Alto Douro (UTAD) 1 article published in JoVE Neuroscience Detection of Abnormal Prion Protein by Immunohistochemistry Leonor Orge1,2, Maria de Lurdes Pinto1, Paula Cristovão2, Paula Mendonça2, Paulo Carvalho2, Carla Lima3, Helena Santos2, Anabela Alves1, Fernanda Seixas1, Isabel Pires1, Adelina Gama1, Maria dos Anjos Pires1 1Animal and Veterinary Research Centre (CECAV), Associate Laboratory for Animal and Veterinary Science-AL4AnimalS, University of Trás-os-Montes and Alto Douro (UTAD), 2Pathology Laboratory, UEISPSA, National Institute for Agricultural and Veterinary Research (INIAV), Oeiras, 3Pathology Laboratory, UEISPSA, National Institute for Agricultural and Veterinary Research (INIAV), Vairão Immunolabeling abnormal prion protein using immunohistochemistry protocols requires specific sample and anti-PrP antibody preparation methodologies. The present protocol describes the key steps in epitope demasking to ensure proper PrP immunolabeling and to minimize non-specific background staining. Also, this approach considers biosafety measures when conducting immunohistochemistry studies with the prion-infected tissues.