Fig. 5.

T cell sub-population proliferation response to in vitro re-stimulation with influenza proteins. Pigs were vaccinated twice (day 0 and 21pv1) i.d. with needle-free delivery with 200 μg (n = 6), 800 μg (n = 6) or 1972 μg (n = 5) DNA, or not DNA vaccinated at all (n = 5). PBMC from the vaccinated pigs on day 35pv1 were cultured in vitro in the presence of recombinant influenza NP 2009, NP 1918, M1 1918 and HA 2009. After 6 days, the cells were stained with anti-CD3, -CD4, and -CD8 monoclonal antibodies and analyzed by flow cytometry. Three T cell subsets were identified based on their CD4 and CD8 expression: (a) CD4-CD8+, (b) CD4+CD8+ and (c) CD4+CD8- cells. Error bars indicate the mean ± SEM, and significant differences from the no-vaccine control group are indicated by: **: p < 0.01; *: p < 0.05.