The invention relates to an agent and/or pharmaceutical active ingredient and to a method for the treatment, prevention and diagnosis of TSE, and to a method for the production of an agent and/or pharmaceutical active ingredient. According to the invention, peptides and/or nucleotide sequences coding for said peptides are provided as disclosed in the sequence protocols 127 and partial sequences thereof are disclosed. Treatment or prevention of the TSE disease, for example, in humans with Jacob Creutzfeldt syndrome, kuru, Gertmann Sträussler-Scheinker syndrome and FFI (fatal familial insomnia) can be carried out with the aid of the inventive peptides. TSE diseases are also known in animals, such as Scrapie in sheep, BSE in cows and CWD in wild animals.