Since host Prnp genotype can significantly affect prion disease survival times and the characteristics of the neuropathology (Dickinson and Fraser, 1977; van Keulen et al., 2015), we next compared CD44 expression in the brains of C57Bl/Dk mice or VM/Dk mice infected with the ME7 or 22A scrapie prion agent strains. Here, PRNP is linked to prion disease.