Beyond PrP9res) type 1/type 2 dichotomy in Creutzfeldt-Jakob disease

Area of Science:

• Neuroscience
• Biochemistry
• Pathology

Background:

• Sporadic Creutzfeldt-Jakob disease (sCJD) classification relies on PRNP codon 129 genotype and prion protein (PrP) Western blot types (1 or 2).
• The co-occurrence of PrP types in CJD cases questions the current classification's basis and link to distinct prion strains.
• Understanding human prion disease variability is crucial for diagnosis and therapeutic strategies.

Purpose of the Study:

• To investigate the biochemical diversity of disease-associated prion protein (PrPSc) in sporadic and iatrogenic CJD.
• To explore an alternative biochemical classification of PrPSc that may better reflect prion agent variability.
• To correlate biochemical PrPSc properties with existing clinico-pathological classifications and PRNP genotypes.

Main Methods:

• Analysis of brain tissue from 41 sCJD and 12 iatrogenic CJD (iCJD) cases.
• Western blotting for proteinase K (PK)-resistant PrP (PrPres) types (1 and 2).
• Two additional biochemical assays assessing PrPSc behavior under variable PK digestion conditions.

Main Results:

• Both PrPres types 1 and 2 were found in 30% of cases, but other assays showed uniform PrPSc biochemical properties within individual patients.
• Four distinct biochemical PrPSc subgroups were identified in sCJD, correlating with clinico-pathological classifications.
• Four similar biochemical clusters were observed in iCJD, independent of PRNP codon 129 polymorphism or PrPres type.

Conclusions:

• The study identifies four distinct biochemical PrPSc subgroups in sCJD and iCJD.
• This biochemical classification offers an alternative to current methods and provides new insights into human prion disease variability.
• Biochemical PrPSc properties are diverse and may represent a more fundamental characteristic of human transmissible spongiform encephalopathy agents.