Enrichment of PrPSc in formalin-fixed, paraffin-embedded tissues prior to analysis by Western blot.

Diagnosis of prion disease is primarily through immunodetection of the infectious agent. Typically, 2 distinct procedures are recommended for a definitive diagnosis, with immunohistochemistry and Western blot providing the most information as to the specific isolate in question. In the past, these approaches required formalin-fixed, paraffin-embedded tissue and fresh or frozen tissue, respectively; however, methods have been developed that allow for use of fixed tissue for Western blot. The present study describes a method of enriching PrP(Sc) in formalin-fixed, paraffin-embedded tissues prior to Western blot analysis for the detection of PrP(Sc). With this modified procedure, 5 times the previously reported sample size may be used for analysis, greatly enhancing the sensitivity of this procedure.