Figure 3.

Recall systemic and mucosal immune responses. The recall humoral immune responses in serum and lung suspensions were determined in vaccinated mice 24 weeks after vaccination and 4 days after challenge in MN and subcutaneously vaccinated mice. Naive (N) uninfected and naive infected mice (Inf) were used as control groups. Total serum HAI (A), IgG titers (B), antibody isotype profile IgG1 and IgG2a (C), lung IgA (D), lung IgG (E), and lung isotype profile (F). Titers and isotype profiles were determined by ELISA. IgG1:IgG2a ratios are shown above the graphs. Data represent the mean ± standard error of the mean (SEM).