Influenza-specific antibody response.

<p>Balb/c mice were immunized according to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072217#pone-0072217-t001" target="_blank">Table 1</a>. Sera were collected at days 20 and 49 and IAV-HA-specific antibody responses were analyzed. To analyze antibodies binding IAV-HA in its membrane bound conformation, the sera were incubated with IAV-HA expressing 293T cells and bound antibodies were subsequently detected by FITC-labeled anti-mouse IgG antibodies. The mean fluorescence intensities (MFI) of each group (means+SEM) are shown for sera from day 20 and day 49 (<b>A</b>). The distribution of IAV-HA-specific IgG1 and IgG2a were analyzed in an ELISA using IAV coated plates and HRP-conjugated anti-IgG1 and IgG2a antibodies. The means and SEM of the relative light units (RLU) are shown for sera from day 49 (<b>B</b>). The neutralizing antibody titer (NT) was analyzed by a microneutralization assay. The reciprocal value of the serum dilution which results in complete protection from infection is given as neutralizing titer. The mean and SEM of each group are indicated for the sera of day 20 and day 49 (<b>C</b>). The results for each group represent at least 12 mice out of 2–3 independent experiments with the exception from the results of group (HA)^low, which based on a single experiment with 6 mice. (p<0.05): <b>*</b> vs. naïve; <b>^#</b> vs. (F)^hi; <b>⁺</b>vs. (HA+F)^low; ^∼ vs. (HA)^low (1 way-ANOVA, Tukey post-test).