PRNP and infection: Specifically, GPI-anchorless PrP Tg mice were found to be susceptible to infection by three scrapie strains, including RML, ME7, and 22L, confirmed by the presence of detectable PrPres and PrP amyloid plaques in the brain by Western blotting and histology; but these mice developed virtually no clinical signs of prion disease during their lifespan [12].