Figure 3. The prevalence of epitope-specific CTL memory cells after primary infection with the H9N2 and H1N1 IAVs.

The primary IAV infection was conducted as described in the legends to Fig. 1. (A) The proportion and (B) number of epitope-specific memory CTL populations and (C) the total number of the three epitope-specific memory CTLs in spleen on d38; (D) The epitope-specific memory CTL populations generated by the priming infection that are cross-reactive with non-conserved epitopes in the H7N9 virus; (E) The total number of epitope-specific memory CTLs generated by primary infection targeting both the conserved and nonconserved epitopes in the H7N9 virus. (A-C) The PB1₇₀₃, PA₂₂₄, and NP₃₆₆ peptide variants specific for each virus were used to stimulate memory CTLs to produce IFN-γ, except for (D) where cross-reactive variants were tested. The data sets represent mean ± SEM, n = 4–5 per group.* p<0.05 by Tukey’s test for (A,B, C, E) or by t test for (D), comparing: (A, B) the indicated epitope versus the other two epitopes; (C, E) the indicated virus versus the other three viruses; (D) the nonconserved versus the counterpart conserved epitope.