To reduce incubation times and number of subpassages for studies of scrapie prions and improve transmission efficiency of CWD prions, transgenic mice were developed to express the ovine or cervid prion protein gene (PRNP), respectively (Browning et al., 2004; Cordier et al., 2006; Crozet et al., 2001; LaFauci et al., 2006; Tamgüney et al., 2006; Vilotte et al., 2001). The gene discussed is PRNP; the disease is scrapie.