Fig. 2. H1Y98F-VLP elicits a more robust and durable antibody response.
Mice were vaccinated (IM) with H1WT- or H1Y98F-VLP (3 µg/dose). Sera were collected at day 21 (left panel) or on a monthly basis (right panel) to measure (a) total H1-specific IgG by ELISA, (b) hemagglutination inhibition titers and (c) microneutralization titers. d Avidity indices of sera obtained 2–7 mpv following incubation with 8 M urea. e H1-specific IgG-producing plasma cells (PC) in the bone marrow measured by ELISpot. Representative wells from each group are shown on the right. f Spearman’s rank correlation technique was applied to evaluate the relationship between the frequency of PC and IgG titers (left), HI titers (middle) and MN titers (right). Error bars represent the mean ± SEM. At day 21, N = 40–70/group and data are pooled from six independent experiments. For long-term studies, N = 7–8/group. Statistical significance between vaccine groups was determined by Mann–Whitney test (*p < 0.033, **p < 0.01, ***p < 0.001). Statistical significance between time points within the same group was determined by two-way ANOVA with the Geisser-Greenhouse correction and Sidak’s multiple comparisons (♦p < 0.033).