CD8A and infection: As shown recently in the mouse model of experimental HCT and infection with mCMV [54], disparities between HCT donor and recipient in major (MHC/HLA) or minor (minor-HAg) histocompatibility antigens in allogeneic HCT (allo-HCT) prevent the reconstitution of high-avidity antiviral CD8 T cells (reviewed in [55]), which would be needed to overcome viral “immune evasion” (reviewed in [56]).