(A) Carboxyl terminal truncations of pp65 localize CTL epitope to a single region. Restriction fragments of pp65 were subcloned into pSC11MCS, and vaccinia viruses were made by techniques discussed in Materials and Methods. The size of the insert in “AA” is indicated by the length of the bars. (B) Identification of boundaries for location of CTL epitope. Either HLA A2 matched (•) or mismatched (×) EBVLCL targets were infected with the series of vaccinia viruses shown in (A). A standard CRA was performed using 10,000 targets at an E:T of 10.