Sera were used in HI assays against the ΔH5N1 virus and in competitive NP-ELISA assays. (A) HI titers at 3 (n=40/group), 6 (n=20/group), and 16 (n=20/group) wpv. (B) Antibodies to NP measured at 6 wpv (n=20 per group). Plotted data: means + standard deviation (SD). Statistical analyses using one-way or two-way ANOVA. *, P<0.05; ***, P<0.001; ****, P<0.0001.