CD27 and infection: Epstein-Barr virus (EBV), a lymphomagenic human herpesvirus, colonises the host through polyclonal B cell-growth-transforming infections yet establishes persistence only in IgD+ CD27+ non-switched memory (NSM) and IgD− CD27+ switched memory (SM) B cells, not in IgD+ CD27− naïve (N) cells.