Figure 4.

CD4+ T cell and CD8+ T cell immune responses in the lungs upon challenge infection with H5N1 or H3N2 influenza viruses. BALB/c mice were intramuscularly immunized twice with the VLPs. Lung samples were collected at 4 days post-challenge infections with H5N1 or H3N2 influenza viruses. Lung cells were gated using the strategy depicted above (A) to determine CD4+ T cell (B,D) and CD8+ T cell (C,E) responses. Immune cells collected from the lungs were stimulated with inactivated viruses (0.5 μg /mL) from H5N1 or H3N2. The lung cells were stained with anti-CD3, CD4, CD8 and the populations were determined by flow cytometry analysis. All data are expressed as mean ± SD (* p < 0.05).