Fig 3. Microscopic lung lesions severity score in M37 hRSV infected neonatal lambs.

(A) Histopathologic lesions included bronchiolitis with degenerate/necrotic individual epithelial cells (thin arrow), occasional syncytial cells (long arrow), accumulation of degenerate neutrophils (short arrow), and occasional macrophages. H&E Bar = 50 μm. (B) A histologic score was given by determining percent consolidation followed by conversion to an integer-based consolidation scale used by our laboratory previously [1]: 0% consolidation = 0; 1%-9% consolidation = 1; 10%-39% consolidation = 2; 40%-69% consolidation = 3; 70%-100% consolidation = 4. Group averages were calculated for alveolar and bronchiolar consolidation scores. In addition to the consolidation score, bronchitis, bronchiolitis, neutrophil infiltration, peribronchiolar and perivascular infiltration of lymphocytes, syncytial cell formation, and epithelial alterations were also scored. Results are indicated as mean ± standard error for each scored parameter.