Stability of PrPres core region after denaturing and basic pretreatment of goat study samples. A The effect of 3.5 M Gdn-HCl treatment on susceptibility to proteolytic degradation was compared to normal condition when analysed by ISS-WB with mAb SAF84. The denaturation yielded high core epitope losses in the CS and CH1641 samples, but not in BSE samples where the PrPres core apparently is highly stable (horizontal axis). The vertical axis shows the susceptibility of the PrPres N-terminus under normal conditions of the ISS-WB process. B The effect of basic pH8 pre-treatment on subsequent proteolytic degradation. Only samples from four countries were tested. The BSE samples appeared the most resistant against proteolytic degradation of the PrPres core. All field samples from Italy, Netherlands, France and Spain together and separately from each country did exhibit a significantly higher susceptibility to Gdn denaturation than goatBSE, as indicated with the P values (Bonferroni–Dunn method).