It has been observed that infection with HCMV changes the composition of the CD4+ and CD8+ memory T cell repertoires; this includes an expansion of the T cell population, which have lost expression of the co-stimulatory molecules CD27 and CD28 but also show re-expression of CD45RA and co-expression of the carbohydrate HNK-1 (CD57) [reviewed in Ref. Here, B3GAT1 is linked to infection.