Fifteen epitopes from various mAb antibodies tested for their potential anti-prion activity were mapped onto the (23–231) PrP primary sequence. Antibodies marked with an asterisk (*) possessed an anti-prion activity and decreased the PrP^Sc levels in prion infected cells or mice (Enari et al. 2001; Heppner et al. 2001; Peretz et al. 2001; White et al. 2003), whereas the others have no inhibitory effect on PrP^Sc molecules. Black boxes or striped boxes represent the epitopes of anti-PrP antibodies. Numbers correspond to amino acid position in the PrP protein.