Immunogenicity and Cross Protection in Mice Afforded by Pandemic H1N1 Live Attenuated Influenza Vaccine Containing Wild-Type Nucleoprotein

Figure 5

Virus-specific CD4+ and CD8+ T-cell responses following immunization of mice with H1N1 LAIVs. Groups of 12 mice were inoculated i.n. with two doses of 10⁶ EID₅₀ of each LAIV virus 21 days apart or mock-vaccinated. Mice splenocytes were collected from 6 mice in each group 21 days after the first dose and 21 days after the second dose. Levels of IFNγ-secreting CD4+ T-cells (a) and CD8+ T-cells (b) were determined after stimulation with SA/wt whole-virus. Bars represent arithmetic mean with SD. Statistical significance of differences was estimated by the Mann–Whitney test. White bars: H1N1 LAIV (6 : 2) rg; grey bars: H1N1 LAIV (5 : 3); black bars: Mock.

(a) CD4+IFN+

(b) CD8+IFN+