Figure 4.

Virus replicon particle (VRP) and polyplex induce a strong and specific CD4⁺ T cell immune response against influenza antigens. Induction of CD4⁺ T cell immune responses against the RepRNA encoded CSFV E2 and influenza virus HA and NP, determined by restimulation of freshly isolated PBMCs and LN cells (day 56 post-first immunization); cells were restimulated with recombinant E2 (1 µg/ml), HA (1 µg/ml) or NP (1 µg/ml), or non-stimulated (-). (A) After 5 days of cell culture, the numbers of division cycles (D0-D7) of proliferating CD4⁺ T cells in PBMC and draining LN compartments, were determined by flow cytometry using the FlowJo software. The values represent the mean of proliferating CD4⁺ T cells of the five individual pigs for each group. Numbers in red represent the mean percentage of highly proliferative cells (≥ 5 division cycles). (B) After 5 days of cell culture, representative dot plots are shown for draining LN compartments of three immunized animals per groups for proliferating CD4⁺ T cells.