Transmission characteristics of heterozygous cases of Creutzfeldt-Jakob disease with variable abnormal prion protein allotypes
Anne Ward, Jason R. Hollister, Kristin L. McNally, Diane Ritchie, Gianluigi Zanusso, Suzette A. Priola
Abstract
Abstract In the human prion disease Creutzfeldt-Jakob disease (CJD), different CJD neuropathological subtypes are defined by the presence in normal prion protein (PrP C ) of a methionine or valine at residue 129, by the molecular mass of the infectious prion protein PrP Sc , by the pattern of PrP Sc deposition, and by the distribution of spongiform change in the brain. Heterozygous cases of CJD potentially add another layer of complexity to defining CJD subtypes since PrP Sc can have either a methionine (PrP Sc -M129) or valine (PrP Sc -V129) at residue 129. We have recently demonstrated that the relative amount of PrP Sc -M129 versus PrP Sc -V129, i.e. the PrP Sc allotype ratio, varies between heterozygous CJD cases. In order to determine if differences in PrP Sc allotype correlated with different disease phenotypes, we have inoculated 10 cases of heterozygous CJD (7 sporadic and 3 iatrogenic) into two transgenic mouse lines overexpressing PrP C with a methionine at codon 129. In one case, brain-region specific differences in PrP Sc allotype appeared to correlate with differences in prion disease transmission and phenotype. In the other 9 cases inoculated, the presence of PrP Sc -V129 was associated with plaque formation but differences in PrP Sc allotype did not consistently correlate with disease incubation time or neuropathology. Thus, while the PrP Sc allotype ratio may contribute to diverse prion phenotypes within a single brain, it does not appear to be a primary determinative factor of disease phenotype.