FIG 3.

Protective efficacy of the different vaccine candidates. Mice were vaccinated once or twice in 4-week intervals and then challenged with 1 × 10⁴ TCID₅₀ of H1N1 PR8 4 weeks later. Upon challenge, animals were monitored daily for clinical signs and body weight and euthanized as soon as the weight loss reached 25%. (A to D) Percent weight changes after challenge following one (A) or two (B) immunizations and the respective percent survivals (C and D) (n = 6; N1 H5N1, n = 5). (E and F) Correlation between mean NI titer and percent survival 4 weeks after the first (E) or the second (F) immunization.