Moreover, adoptively transferred CD137−/− OVA-specific OT-I and OT-II cells hyperproliferated in WT B6 mice (26, 41), and CD137−/− mice had increased numbers of primary CD8+ T cells and fewer memory CD8+ T cells during chronic/latent infection with mouse CMV (79). Here, CD8A is linked to disease arising from reactivation of latent virus.