We also showed that Prnp0/0 mice transgenic for mouse PrP with substitutions of lysine residues at positions 23, 24, and 27 to alanine residues, or PrP3K3A, markedly reduced their susceptibility to RML and 22L scrapie prions (Table 1) [66], suggesting that positively charged residues in residues 23–24 and 27–31 could be important for the polybasic region to support prion pathogenesis. This evidence concerns the gene PRNP and scrapie.