PRNP and infection: To better understand whether HSC senescence in ME7-infected mice is progressively caused by impairment of the BM microenvironment, we performed a non-competitive transplantation experiment that involved transplanting BM cells (2 × 106, CD45.1) from Prnp+/+ (WT) or Prnp−/− (KO) mice, as confirmed by PCR (Supplementary Fig. S12A), into control or ME7-infected mice that had received sub-lethal irradiation at 3 months post-infection (CD45.2, 5 Gy, Fig. 6A).