For example, it is plausible that transcriptional downregulation of PSMB5 concomitant with upregulation of PSMB8 might be beneficial upon viral infection, when immunoproteasomes are favored to increase the production of antigenic peptides60,61, or during thymic development when PSMB11 (β5t) is incorporated in preference to PSMB5 and PSMB8 into the thymoproteasome62. Here, PSMB11 is linked to viral infectious disease.