BTLA and Epstein-Barr virus infection: With respect to receptor co-expressing subsets, mainly PD-1+Tim3+KLRG1+, PD-1+Tim3+KLRG1-, PD-1+2B4+BTLA+, and PD-1+2B4+BTLA- CD8+ T cell populations expanded during symptomatic primary EBV infection in huNSG mice (Fig 6C and S7B Fig).