In addition to other viral infections such as chronic human HIV [59,60], HBV [61,62], HCV [63] and malaria [64], CD8+ T cells exhibiting a similar exhausted phenotype have also been described both in murine tumour models, and in tumour-infiltrating lymphocytes (TIL) isolated from solid human tumours [65,66,67,68]. Here, CD8A is linked to viral infectious disease.