Detection of Type 1 Prion Protein in Variant Creutzfeldt-Jakob Disease

Abstract

Molecular typing of the abnormal form of the prion protein (PrP Sc) has come to be regarded as a powerful tool in the investigation of the prion diseases. All evidence thus far presented indicates a single PrP Sc molecular type in variant Creutzfeldt-Jakob disease (termed type 2B), presumably resulting from infection with a single strain of the agent (bovine spongiform encephalopathy). Here we show for the first time that the PrP Sc that accumulates in the brain in variant CreutzfeldtJakob disease also contains a minority type 1 component. This minority type 1 PrP Sc was found in all 21 cases of variant Creutzfeldt-Jakob disease tested, irrespective of brain region examined, and was also present in the variant Creutzfeldt-Jakob disease tonsil. The quantitative balance between PrPSc types was maintained when variant Creutzfeldt-Jakob disease was transmitted to wild-type mice and was also found in bovine spongiform encephalopathy cattle brain, indicating that the agent rather than the host specifies their relative representation. These results indicate that PrP Sc molecular typing is based on quantitative rather than qualitative phenomena and point to a complex relationship between prion protein biochemistry, disease phenotype and agent strain.

A refined method for molecular typing reveals that co-occurrence of PrPSc types in Creutzfeldt–Jakob disease is not the rule

“…We agree with Yull et al 35 and Polymenidou et al 34 that the detection of type 1 and 2 co-occurrence using a conventional typing method and antibodies recognizing both types may lack sufficient sensitivity. In this regard, we were able to increase the sensitivity of the type 1 and 2 co-occurrence signal up to the value of 10% (weak band of one type/total PrP Sc ) using a conventional gel electrophoresis system and up to Figure 8 Detection limit of PrP Sc types 1 and 2 co-occurrence by 3F4.…”

“…PrP Sc types co-occurrence in CJD S Notari et al that PrP Sc type 1 regularly coexist in CJD previously classified as type 2. 34, 35 We also detected a type 1-like band in all CJD type 2 subtypes but came up to a different conclusion concerning the origin and biological significance of this band. In a previous study, 30 where we originally applied a highresolution electrophoretic system, which better discriminates between distinct PrP isoforms, we showed that PK digestion of both PrP Sc types 1 and 2 produces additional fragments migrating slightly slower than the resistant core.…”

“…17,19,29,44 Yull et al 35 found that the type 1-like band detected by 12B2 in vCJD maintained the very characteristic glycoform ratio of PrP Sc type 2B and concluded that the band they considered a PrP Sc resistant core could not be a common type 1. We consider this result, which was also reproduced by us, as further evidence that the type 1-like band recognized by 12B2 in vCJD cases represents partially cleaved fragments of PrP Sc type 2B rather than real, bona fide PrP Sc type 1.…”

“…[31][32][33] Nevertheless, difficulties remain in understanding both the biological basis of this phenomenon and its prevalence. The issue has become particularly puzzling after two recent studies 34,35 took advantage of monoclonal antibodies recognizing an epitope between residues 82 and 96 of human PrP located outside the primary PK cleavage site of type 2 PrP Sc . These studies showed that all CJD cases classified as type 2, using standard antibodies, also contain a variable amount of PrP Sc that matches PrP Sc type 1 in gel migration characteristics after PK treatment.…”

Disease‐associated prion protein is not detectable in human systemic amyloid deposits

“…The 3F4 and 6H4 antibodies both detect epitopes present in denatured PrP C and PrP Sc . Their specificity for PrP res in Western blotting is dependent on the presence of the 3F4 and 6H4 epitopes in the protease-resistant core fragment of PrP res [11,12,26]. The 3F4 antibody (CE marked) has been consistently used for over 10 years in diagnostic testing for human prion disease by the majority of human prion disease surveillance and research centres worldwide [11,12,27,28].…”