Researchers from the United Kingdom and France have identified four separate biochemical subgroups in a selection of cases of Creutzfeldt-Jakob disease. The study suggests that these subgroups could represent distinct prion strains in what is the most common human prion disease.
Prion diseases are transmissible neurodegenerative disorders characterized by accumulation of an abnormal isoform (PrPSc) of a host-encoded protein (PrPC) in affected tissues. Although considered a spontaneous disorder, the clinicopathological characteristics of sporadic Creutzfeldt-Jakob disease (sCJD) are variable and substantially influenced by a particular variation in the DNA of the prion protein gene (PRNP).
Due to the strong influence of host factors on the characteristics of the disease, diversity of prion agents responsible for CJD remains extremely difficult to investigate.
In this study, using two new biochemical assays, the authors identified four distinct biochemical PrPSc subgroups in 41 sCJD cases. These subgroups correlate with the current sCJD subclassification. The subgroups were also found in 12 iatrogenic CJD (iCJD) cases from different countries. Iatrogenic CJD occurs following human-to-human sCJD transmission. In contrast to the sCJD cases, however, there was no particular correlation with the PRNP codon in the iCJD cases, indicating that observed biochemical properties could be specific to the prion agent.
Further studies are required to confirm that the four biochemical subgroups identified correlate with distinct biological infectious agents.
Journal reference: Uro-Coste E, Cassard H, Simon S, Lugan S, Bilheude J-M, et al. (2008) Beyond PrPres Type 1/Type 2 Dichotomy in Creutzfeldt-Jakob Disease. PLoS Pathog 4(3): e1000029. doi:10.1371/journal.ppat.1000029 (http://www.plospathogens.org/doi/ppat.1000029)
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