Fig 1.
IgG-specific antibodies and neutralizing antibodies in serum.
Mice were vaccinated on weeks 0, 3 and 6 and were infected intranasally (i.n.) with hRSV A Long (1×105 PFU) on Day 143. Bleeds were collected every 3 weeks. (A) Dynamic changes in IgG-specific antibodies at 21 weeks. (B) Dynamic changes in neutralizing antibodies at 21 weeks. Serum neutralization titers against hRSV A Long were measured at Week 21. The titers were presented as dilution factors resulting in a 50% reduction in plaque numbers. Statistically significant differences were measured by one-way ANOVA with Newman–Keuls posttest. *** p<0.001, **p<0.01, * p<0.05.
Fig 2.
IgG1 and IgG2a titers on Day 4 after hRSV A long challenge.
(A) IgG1 titers on Day 4 after hRSV A long challenge. (B) IgG2a titers on Day 4 after hRSV A Long challenge. (C) IgG1/IgG2a ratio on Day 4 after hRSV A long challenge. Statistically significant differences were measured by one-way ANOVA with Newman–Keuls posttest. *** p<0.001, **p<0.01, * p<0.05.
Fig 3.
Numbers of IL-4- and IFN-γ-secreting splenocytes.
ELISPOT assays were used to detect IL-4- and IFN-γ-secreting lymphocyte cells in the spleen. Splenocytes were stimulated with F protein (expressed in 293F cells, 10 μg/mL) for 16 h. (A) Numbers of IFN-γ secreting splenocytes. (B) Numbers of IL-4 secreting splenocytes. (C) Ratio of IL-4-secreting splenocytes and IFN-γ-secreting splenocytes. Statistically significant differences were measured by one-way ANOVA with Newman–Keuls posttest. *** p<0.001, **p<0.01, * p<0.05.
Fig 4.
Intracellular IL-4 and IFN-γ production by CD4+ T cells.
(A) The spots in the rectangular box represent IFN-γ-secreting or IL-4-secreting CD4+ T cells. (B) The percentages of CD4+ T cells producing IFN-γ or IL-4. (C) Ratio of IL-4-secreting CD4+ T cells and IFN-γ-secreting CD4+ T cells.
Fig 5.
Intracellular IL-4 and IFN-γ production by CD8+ T cells.
(A) The spots in the rectangular box represent IFN-γ-secreting or IL-4-secreting CD8+ T cells. (B) The percentages of CD8+ T cells producing IFN-γ or IL-4. (C) Ratio of IL-4-secreting CD8+ T cells and IFN-γ-secreting CD8+ T cells. Statistically significant differences were measured by one-way ANOVA with Newman–Keuls posttest. *** p<0.001, **p<0.01, * p<0.05.
Fig 6.
Histopathology analysis of H&E-stained.
(A) Left lungs were stained with hematoxylin and eosin (H&E) for histologic evaluation. (B) Scoring of alveolar wall thickening after hRSV challenge of immunized mice. (C) Scoring of bronchiolitis after hRSV challenge of immunized mice. (D) Scoring of interstitial pneumonitis after hRSV challenge of immunized mice. Scores ranged from 0 (normal) to 4 (severe). Statistically significant differences were measured by one-way ANOVA with Newman–Keuls posttest. *** p<0.001, **p<0.01, * p<0.05.