Histopathology and cytokine/chemokine levels in the lungs of animals vaccinated with the REG 67–298, REG ΔCCD, REG 67–163, and REG 187–298 at day 5 following RSV challenge.

(A) Lung tissues were collected at 5 days post-challenge and were stained with hematoxylin and eosin. Individual lungs were scored for pulmonary inflammation: bronchiolitis (mucous metaplasia of bronchioles), perivasculitis (inflammatory cell infiltration around the small blood vessels), interstitial pneumonia (inflammatory cell infiltration and thickening of alveolar walls), and alveolitis (cells within the alveolar spaces). Slides were scored blindly using a 0–4 severity scale. The scores were subsequently converted to a 0–100% histopathology scales. (B-I) Levels of cytokines and chemokines in lung homogenates from day 5 post challenge were measured in a Bio-Plex Pro mouse cytokine assay. Values are cytokine/chemokine concentrations, expressed in pictograms per milliliter. The mean for each group is shown. (J) Ratio of the observed concentrations of IL-4 vs. IFNγ shown in panels B and F. Statistical significance was tested by one-way ANOVA and Bonferroni multiple-comparison tests. *, p <0.05.