Figure 4

Lung pathology of mice infected with various strains of H1N1 at 5 dpi. A. Lung from an animal infected with strain INER307 showing that lesions are limited to bronchioles with necrosis, epithelial hyperplasia and peribronchiolar infiltrates of lymphocytes and plasma cells (arrow). H&E stain. B. Lung from an animal infected with strain INER405 shows bronchiolitis (arrowhead) and small areas of alveolar involvement (arrow). H&E stain. C. Lung from an animal infected with strain INER111 showing widespread inflammation and necrosis of alveolar walls. Note small area of consolidation with neutrophilic infiltrate (arrow). H&E stain. D. Lung from an animal infected with strain INER047 showing large areas of consolidation due to neutrophilic infiltrate (*). H&E stain. E. Lung from a non-infected control animal. H&E stain. Bar = 100 μm.