PRNP and infection: However, Tg(PrP∆32–93)/Prnp0/0 mice, which express PrP with a deletion extending to the post-OR region at position 93 from the OR region at position 88, developed disease with longer incubation times and with lower levels of infectivity and PrPSc∆32–93 in their brains after infection with RML prions (Table 3) [81].