Challenge with A/New Caledonia/20/99 (H1N1).

<p>6 to 10 months-old ferrets were immunized twice at two week- intervals with CAF01 adjuvanted (▴) and non-adjuvanted (▪) influenza vaccine Sanofi-Pasteur's Vaxigrip season 2005/2006 (n = 8 per group). A third group was mock-vaccinated (•). All ferrets were challenged with 10⁷ TCID₅₀ of A/New Caledonia/20/99 (H1N1) four weeks after the second immunization (n = 8 per group). <b>A.</b> Relative amounts of viral RNA found in nasal washes of infected animals during the first six days of challenge, measured by quantitative RT-PCR. <b>B.</b> Vaccine-specific IgG titers measured in serum by ELISA <b>C.</b> Vaccine-specific IgA titers measured in nasal washes by ELISA. <b>D.</b> Hemagglutination inhibition assay titers using influenza A New Caledonia 1999 (H1N1). All ELISA values are expressed as geometric mean titers (GMT). <b>E.</b> Percentage of IFN-γ-positive lymphocytes after 4 hours stimulation with PMA and ionomycin. Values marked with an asterisk are significantly different (*, <i>p</i><0.05; **, <i>p</i><0.01; ***, <i>p</i><0.001), assessed by ANOVA, except for B assessed by log-rank test.