FIG. 4.

T-cell cytokine production and RSV-specific antibody responses following recombinant RSV infection. Four-day-old BALB/c mice were infected with 8 × 10⁴ FFU of RSV/wt (black bars), RSV/IFN-γ (hatched bars), or RSV/IL-4 (lined bars) i.n. or left naïve (open bars). (A and B) On day 14 postinfection, PMA-ionomycin-stimulated CD4 T cells were stained for the intracellular presence of IFN-γ (A) and IL-4 (B). (C) At the same time point, CD8 T cells were stained with an RSV M2-specific pentamer. (D) Serum was taken at 14 days postinfection, and the level of RSV-specific Ig was determined by ELISA. Data are representative of two experiments, and points represent data for five mice per group ± SEM. *, P < 0.05; **, P < 0.01.