FIG 8.

Challenge of ferrets with A/California/07/2009 influenza virus. Sing/86 preimmune ferrets (n = 4) were vaccinated on day 84 with each vaccine plus the AF03 adjuvant and then infected on day 168 with CA/09 (10⁶ PFU). Naive ferrets infected with CA/09 were utilized as negative controls. (A) Ferrets were monitored daily for weight loss over an 8-day observation period. Values are average percentages of original weight plus the SEM (error bars). (B) Viral titers were determined from nasal washes collected at days 1, 3, and 5 postchallenge. Bars indicate mean virus titers ± the standard deviations (SD). (C) Antibody titers against the HA stem were evaluated on day 84 (white bars) and day 98 (14 days postvaccination) (black bars) postinfection by ELISA. Data are presented as means ± the SD for each treatment group. (D) Antibody titers against the HA stem were evaluated at 14 days postchallenge. Data for individual ferrets within each group are plotted, along with means ± the SD. The antibody titers in panels C and D are reported as the serum dilution yielding a half-maximal signal (EC₅₀). Significance was determined using paired or unpaired t tests (*, P < 0.05; **, P < 0.01).