Higher recall immune responses induced by trehalose stabilized microneedle vaccine.

<p>Lung, serum, and spleen samples were collected from individual mice in each group (n = 6) at day 4 post challenge. (A) Virus specific IgG1 and IgG2a antibodies in lungs (ng/g tissue: ng antibodies per g lung tissue). (B) Virus specific IgG1 and IgG2a antibodies in sera (ng/ml: ng antibodies per ml sera). (C) IFN- γ secreting splenocytes (spots/1×10⁶ spleen cells) after stimulation with hemagglutinin-specific MHC I and II peptides. (D) Neutralizing activities in lung. Serial dilutions of lung samples were incubated with infectious influenza viruses and percentiles of plaque forming units were determined. Titers/g tissue: dilution factors per g lung tissue from the lung extracts (0.25 g/ml). Groups of mice are the same as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007152#pone-0007152-g005" target="_blank">Fig. 5</a>. Significant differences were found among the groups: For lung IgG2a antibody (A), p<0.001 between MN+T and other groups; for lung IgG1 (A), p<0.001 between MN+T and IM or IM+T. For serum IgG2a antibody (B), p<0.001 between MN+T and other groups; for IgG1 (B), p<0.005 between MN and IM or IM+T, p<0.05 between MN+T and IM or IM+T. For spleen IFN-γ secreting cells (C), p<0.05 between MN+T and other groups. For lung neutralizing titers, p<0.05 between MN+T and other groups at 15× dilution.