Inter-Laboratory Assessment of PrPSc typing in Creutzfeld-Jakob Disease: A Western Blot Study within the NeuroPrion Consortium

Molecular typing in Creutzfeld-Jakob disease (CJD) is of considerable importance for the surveillance and epidemiology of human transmissible spongiform encephalopathies (TSE). It relies on the detection of distinct protease-resistant prion protein (PrPSc) core fragments that differ in molecular mass and/or glycoform ratio. In this collaborative study we tested the interlaboratory agreement in CJD molecular typing. Sixteen characterised speciment from brains of cases of sporadic and variant CJD were distributed blindly to seven laboratories for molecular characterisation by a defined protocol and classification. Agreement in the classification of samples between laboratories was excellent. In particular, there were no differences in the distinction between type 1 and type 2 samples with one exception, which eventually was identified as a case with type 1 and type 2 co-occurence. This shows that the general technique and particular classification systm used here are robust and therefore can be considered as a reliable basis for diagnostic and epidemiologic purposes. The subtle distinction between subtypes amongst type 1 and type 2 bands must be reserved for special investigations using long gel equipment. Further research is necessary on the identification and significance of co-occurence of type 1 and type 2 PrPSc within one brain.JRC.D.2-Reference material