Shwetank, et al. – In this study, experts aimed at determining whether maintenance of programmed cell death protein 1 (PD–1) on brain–resident memory CD8 T cells was antigen independent. After being demethylated during acute infection, the PD–1 promoter of splenic antiviral memory CD8 T cells subjected to remethylation. Data indicated PD–1 expression as an intrinsic property of brain T_RM cells in a persistent central nervous system (CNS) viral infection.