Figure 3: Cytokine production by vaccine-induced NP-specific CD8+ T cells. Groups of young and aged mice were either vaccinated with 1010 vps of AdC68NP only (young and aged: each) or were then subsequently boosted 8 weeks later with 0.8 × 105 TCID50 of A/X31 (young: , aged not tested as all died following infection). Additional age-matched groups were added that received only A/X31 boost (young and aged: each). All mice were then challenged with 3LD50 A/PR8 2 months following the boost, along with age-matched control groups (young: , aged: ). At day 20 following the challenge, splenocytes were isolated, and an ICS was conducted to detect production of IFN-γ (G), IL-2 (I), and TNF-α (T).