FIGURE 2.

Gross and histopathology. Pigs were immunized twice 21 d apart with either homologous inactivated vaccine i.m. (Homologous) or H3N2 S-FLU by aerosol (S-FLU). Controls were unimmunized animals. Animals were challenged with 1353/09pdmH1N1 on 28 or 30 dpb. Animals were sacrificed at 5 dpc, and lungs were scored for appearance of gross pathology (A) and histopathological lesions (B). Each data point represents an individual within the indicated group, and bars represent the mean. (C) Gross pathology, histopathology (H&E), and immunohistochemical NP staining of representative lungs for each group are shown. Areas of purple-red consolidation (green arrows) are present in lungs from infected groups. Microscopic lesions include alveolar septal inflammation, peribronchiolar inflammatory cell cuffing, and necrotizing/suppurative bronchiolitis with presence of NP Ag in bronchiolar epithelial cells and inflammatory cells (black arrows). Original magnification ×400. Asterisks denote significant differences from the control group. **p < 0.01, ***p < 0.005, determined using one-way ANOVA with Dunn test for multiple comparisons.