Table 2.

Pulmonary pathological features of mice infected with RSV and/or IAV.

Group		Severity of inflammation		Infiltrated cells		Vascular changes		Pulmonary oedema	Alveolar and interstitial changes
		Description	Score (0–5)	Description	Score (1–10)	Description	Score (0–3)	Description	Description
Uninfected		Very mild or no inflammation	0	Very mild or no infiltrated cells	0	Normal vascular morphology	0	No pulmonary eodema	Normal parenchyma architecture was observed
INF (I)	Day 2	Mild inflammation in the interstitum	1	Mild infiltration dominated by neutrophils	3	Congested vasculature especially in the capillary	1	Moderate bronchiolar oedema	Moderate, diffuse and localized thickening of the respiratory bronchiolar epithelium. Desquamation of the walls delineating the bronchioles and alveolar duct
	Day 4	Widespread but diffuse inflammation with bronchial and epithelial proliferation	2	Severe and predominantly lymphocytic	7	Severe vascular congestion	3	Extensive eodema in the bronchiolar lumen and moderate interstitial oedema	Severe alveolar compression and loss of peri-bronchiolar wall
	Day 7	Widespread and severe inflammation affecting the interstitium, bronchi and alveoli	4	Predominantly lymphocytes and neutrophils	10	Moderate vascular congestion	2	No oedema	Severe parenchyma thickening that occluded almost all the parenchyma lumen
RSV (R)	Day 2	Diffused inflammation was noted	1	Mild infiltration dominated by neutrophils	4	Congested inter-alveoli capillary congestion	1	Oedema was conspicuously absent	Widespread thickening of the alveolar and bronchiolar walls.
	Day 4	Moderate to severe inflammation spanning wide area of the parenchyma.	3	High infiltration of inflammatory cells which are chiefly lymphocytes and neutrophils	6	Moderate to severe vascular congestion	2	Apparent oedematous alveoli which continued in the alveoli duct. Few oedematous respiratory bronchioles.	Severe alveolar compression widespread parenchyma thickening
	Day 7	Severe foci of inflammation affecting major portions of the interstitium and bronchi	4	Predominantly lymphocytes	7	Moderate to severe vascular congestion	2.5	Moderate oedema commonly seen in the alveolar duct	Formation of emphysema, severe thickening of interstitium and moderate alveolar compression
IR	Day 2	Moderate inflammation. No bronchial involvement	1	moderate lymphocytes and neutrophils	3.5	Moderate vascular congestion	2	Traces of Moderate eodema was seen in one of the representative photomicrographs. This was peculiar to certain alveolar duct loci	Mild alveolar compression with diffuse moderate interstitial thickening
	Day 4	Diffuse broncho-interstitial inflammation	2	Lymphocytic infiltration with traces of neutriphils	5	Mild to moderate congestion	1.5	Mild alveolar oedema	Moderate localized and diffused thickening with broncho-epithelial cells desquamating into the lumen
	Day 7	Acute and moderate broncho-interstitial pneumonia	3	Predominantly lymphocytes and neutrophils	6.5	Moderate to severe vascular congestion	2	Moderate oedema in the alveolar sac. The oedema also migrated to the lumen of the adjoining alveoli.	Severe, diffuse interstitial thickening with evidence of fibrosis. There is emphysema formation.
RI	Day 2	Moderate inflammation. No bronchial involvement	1	Mild cellular infiltration comprising both neutrophils and lymphocytes	2	Mild to moderate capillary congestion	1.5	Very mild oedema	Moderate and diffuse interstitial thickening. Loss of epithelial integrity of certain epithelial bronchioles
	Day 4	Acute and moderate inflammation with bronchial epithelial thickening	2	Predominantly lymphocytic	6.5	Mild to moderate congestion	1.5	Mild oedema that spans the longitude of the bronchiole	Mild to moderate diffuse interstitial thickening
	Day 7	Acute and moderate thickening inflammation. Bronchial thickening was evident and intrabronchiolar debris was noted	2	Predominantly lymphocytic infiltration with lymphocyte-neutrophil ratio of about 70–30.	7	Mild to moderate capillary congestion	1.5	Very mild oedema	Emphysema formation, compression of alveoli and interstitial thickening
I + R	Day 2	Mild inflammation. No bronchial involvement	1	Lymphocytes and neutrophils of almost equal proportion	4	mild to moderate congestion	1..5	Moderate interstitial oedema	Compression of alveoli, mild to thickening by cellular infiltration
	Day 4	Acute and diffuse broncho-interstitial inflammation. Mild thickening of bronchial epithelium which ran along the bronchiolar tree	1	Predominantly lymphocytes and neutrophils in 40–60 ratio	6	Moderate to severe vascular congestion	2	Moderate oedema in the alveolar sac.	Multifocal areas of intracellular thickening and moderate alveolar compression
	Day 7	Acute and moderate alveolitis	3	Predominantly lymphocytes and neutrophils in 50-50 ratio	7	Moderate vascular congestion	1.5	Oedema was evident in a single respiratory bronchiole. Generally, a mild oedema was seen in the pulmonary parenchyma	Mild and diffuse interstitial thickening