FIG. 1.
Systemic responses to BRSV. (A) BRSV-specific IgG 2 weeks after the second immunization. (B) Kinetics of the BRSV-specific IgG response. (C) BRSV-specific IgA after challenge. (D) Virus neutralizing antibodies after challenge. (E and F) Numbers of IFN-γ-secreting (E) and numbers of IL-5-secreting (F) splenocytes in response to in vitro restimulation with BRSV-infected cell lysates. Mice were immunized i.n. with FI-BRSV-CpG, FI-BRSV-PP, FI-BRSV-CpG-PP, or saline. CpG ODN was given at 4 μg per immunization, and PP was given at 25 μg per immunization. All animals were challenged with BRSV 2 weeks after the second immunization (except for the saline/saline group). Five of the mice were euthanized 4 days later and the other half 6 days later. Cytokine production was measured 6 days after challenge. Virus neutralization titers are expressed as the highest dilution of serum that resulted in less than 50% of cells displaying cytopathic effects. Cytokine-secreting cells are shown as the difference between the number of cytokine-secreting cells per 106 cells in BRSV-infected lysate-stimulated wells and the number of cytokine-secreting cells per 106 cells in mock-infected lysate-stimulated wells. In panels A, C, D, E, and F, each data point represents an individual animal, and median values are indicated by horizontal bars. In panel B, median values are shown. *, P < 0.05; **, P < 0.01; ***, P < 0.001.