PRNP and variant Creutzfeldt-Jakob disease: We then compared the amounts of total PrP in CNS samples of the myelopathic primates to the amounts in healthy, c-BSE, and v-CJD primates by directly testing homogenates by ELISA without a prior step of proteolysis purification but after simple addition of the denaturation buffer (chaotropic agents and detergents), without the successive heating treatment that unfolds abnormal PrP.