Immunoquantitative PCR for prion protein detection in sporadic Creutzfeldt-Jakob disease

Abstract

Background: The most common human prion disorder is Creutzfeldt-Jakob disease (CJD); it includes sporadic, familial, iatrogenic, and variant subtypes. Diagnostic tests aim at detection with the highest specificity of very small deposits of abnormal prion protein (PrP). Methods: We used immunoquantitative PCR (iqPCR) to detect proteinase K-resistant PrP (PrPRes) in tissue from the middle frontal gyrus of 7 patients with sporadic CJD and 7 non-CJD cases. We compared iqPCR with routine optimized ELISA, Western blotting, and immunohistochemical analyses. Results: The 4 methods showed similar 100% sensitivity and specificity for the diagnosis of CJD. Along with high specificity, however, iqPCR had a threshold for PrPRes detection at least 10-fold lower than that of the classic ELISA. Conclusions: iqPCR is a new method for PrPRes detection that combines 100% specificity with a detection threshold at least 10-fold lower than classic techniques. This method may improve the detection of minute PrPRes deposits in tissues and body fluids and thus be useful for diagnostic and sterilization applications. © 2005 American Association for Clinical Chemistry.