CD38 and viral infectious disease: To gain deeper insight into the instructions of the viral context in driving CD38 expression on virus-specific CD8+ T cells, we analyzed CD38 expression data from our previously published study in which we investigated responses at day 50 after infection in controlled experimental models of acute lymphocytic choriomeningitis virus–Armstrong strain (LCMV-Armstrong), low-level persistent (mouse CMV [MCMV]) and high-level chronic (LCMV-clone 13) viral infection using mass cytometry (31).