However, it is becoming increasingly evident that multiple factors contribute to CD8+ T‐cell expansion.9, 18, 19 For example, the number of naïve CD8+ T cells specific for DbNP366 and DbPA224 is significantly lower than the number of naïve CD8+ T cells specific for the KbNS2114 and DbPB1‐F262 epitopes prior to infection. This evidence concerns the gene CD8A and infection.