Fig. 3. Cross-reactivity of virus-specific polyclonal CD8⁺T-cells assessed by IFN-γ ELISpot. (a) B/Victoria/2/1987 virus-specific polyclonal CD8⁺T-cells or (b) B/Yamagata/16/1988 virus-specific polyclonal CD8⁺T-cells of nine study subjects were co-cultured with HLA-matched BLCLs infected with B/Victoria/2/1987, B/Netherlands/455/2011, B/Yamagata/16/1988 or B/Netherlands/712/2011.The number of IFN-γ-producing cells per 10 000 polyclonal CD8⁺T-cells was determined by ELISpot assay. Experiments were performed in triplicate; bar, sd. Uninfected BLCLs were used as negative controls. Identification number of the respective study subject is indicated in the left upper corner of each graph.