Epstein‐barr virus‐specific t‐cell recognition of B‐cell transformants expressing different ebna 2 antigens

Epstein‐Barr (EB) virus isolates can be classified as type A or type B depending upon the identity of the virus‐encoded nuclear antigen EBNA 2; the EBNA 2A and 2B proteins show limited amino‐acid homology and induce largely non‐cross‐reactive antibody responses in humans. To examine whether EBNA 2 might also be a target for virus‐specific cytotoxic T‐cell responses (like “intracellular” antigens in other viral systems), normal B cells from non‐immune donors of known HLA type were transformed in vitro with virus isolates either of type A (from the B95‐8 and IARC‐BL74 cell lines) or of type B (from the AG876 and IARC‐BL16 cell lines) to provide a suitable panel of target cells. DNA hybridization with type‐specific probes and immunoblotting with type‐specific antisera confirmed the EBNA 2 type of the resident virus in the various in vitro transformants. These cells were then tested as targets for virus‐specific cytotoxic T cells, the latter being prepared from type‐A virus‐infected donors by in vitro reactivation of memory cells from peripheral blood using autologous type‐A virus‐transformed cells as stimulators. Such effector cells lysed type‐A virus‐transformed and type‐B virus‐transformed target cells equally well, indicating that EBNA 2 (in particular that part of the protein which varies between virus types) seems not to be a dominant antigen for the induction of EB virus‐specific cytotoxic responses.