Novel method for classification of prion diseases by detecting PrP^res signal patterns from formalin-fixed...

Area of Science:

• Neurology
• Biochemistry
• Pathology

Background:

• Prion diseases are fatal, infectious neurodegenerative disorders.
• Definitive diagnosis relies on detecting proteinase K (PK)-resistant prion protein (PrP^res) via Western blotting (WB).
• Formalin-fixed paraffin-embedded (FFPE) tissues are commonly used for histopathology but challenging for biochemical prion detection.

Purpose of the Study:

• To establish a method for detecting PrP^res in FFPE specimens from various prion disease types.
• To correlate biochemical PrP^res detection with histopathological findings.
• To enable classification of prion diseases using FFPE samples.

Main Methods:

• FFPE tissue samples from sporadic Creutzfeldt-Jakob disease (sCJD), Gerstmann-Sträussler-Scheinker disease (GSS), glycosylphosphatidylinositol-anchorless prion disease (GPIALP), and V180I CJD were treated with formic acid to inactivate infectivity.
• Following deparaffinization, samples underwent PK digestion and protein extraction.
• PrP^res detection was performed using specific antibodies, including those targeting PrP^res types 1 and 2, prion protein core, and the C-terminus.

Main Results:

• A pronounced PrP^res signal was observed in sCJD, with varying antibody reactivity.
• Histological examination correlated with biochemical findings.
• PrP^res bands (8-9 kDa) and smears were detected in GSS and GPIALP using core-specific antibodies, but C-terminal antibody showed smears in GSS and no detection in GPIALP.
• Detection of PrP^res in V180I CJD was challenging.

Conclusions:

• PrP^res can be detected in FFPE tissues, enabling prion disease classification.
• This approach integrates histopathological and biochemical analyses on the same sample.
• Inactivation of infectivity makes the method safe and valuable for prion disease diagnosis and research.