ELISPOT analysis of IFN-γ production by HA_533–541 specific T cells in vaccinated mice at 42 days after immunization.

<p>Mice were immunized intragastrically at day 0, 14, and 28 with PBS, the commercial H5N1 vaccine (cv-H5N1), and <i>Salmonella</i> SL368 carrying the empty vector pVAX1 (Sal-vector) and constructs p5HA and p5NA (Sal-HA-NA). Splenocytes (n = 5) were harvested from immunized mice at 42 days post immunization and stimulated with HA_533–541 peptide for 48 hours. The results were expressed as spot-forming cells (SFC) per million cells. The assays were performed in triplicate and the experiments were repeated three times. The values obtained were the average from these experiments. Statistical analysis was performed by two-way ANOVA. *<i>p</i> < <i>0</i>.<i>01</i>.