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

Figure 6

Cytotoxic activity of CTLs following immunization of mice with H1N1 LAIVs. Groups of 8 mice were inoculated i.n. with two doses of 10⁶ EID₅₀ of each LAIV virus 21 days apart or mock-vaccinated. Splenocytes from naive C57BL/6 mice were loaded with SA/wt virus and adoptively transferred by retroorbital injection to vaccinated mice on day 21 after the second dose. The next day, specific cytotoxicity was measured and represented as the ratio of the count of virus-loaded target cells to that of control target cells. Bars represent arithmetic mean values with SD. Statistical significance of differences was estimated by Mann–Whitney test. Triangles: H1N1 LAIV (6 : 2) rg; squares: H1N1 LAIV (5 : 3) rg; circles: Mocks.