TABLE 2.

Comparison of histopathological changes induced by infection with wt RSV or RSV/IL-4^a

Day	Virusb	Mean score ± SE (P)c,d
		Peribronchiolitis	Perivasculitis	Interstitial pneumonitis	Alveolitis
4	wt RSV	2.5 ± 0.8	4.5 ± 0.5	0.5 ± 0.5	0
	RSV/IL-4	17.0 ± 3.3 (<0.001)	24.0 ± 6.4 (<0.01)	13.0 ± 3.3 (<0.01)	4.5.0 ± 0.5 (<0.001)
	Mock	1.2 ± 1.2	1.2 ± 1.2	0	0
8	wt RSV	17.0 ± 3.3	19.0 ± 3.1	9.0 ± 3.6	2.5 ± 0.8
	RSV/IL-4	23.0 ± 2.0	15.0 ± 3.3	3.5 ± 2.5	2.0 ± 0.8
	Mock	0	1.2 ± 1.25	0	0
32 (4)	wt RSV	30.6 ± 5.6	77.8 ± 2.8	20.6 ± 10.6	8.3 ± 3.2
	RSV/IL-4	28.0 ± 5.6	62.5 ± 8.5	14.5 ± 3.5	13.5 ± 7.1
	Mock	3.7 ± 1.2	10.0 ± 5.0	0	0
36 (8)	wt RSV	28.0 ± 5.6	60.0 ± 7.6	2.5 ± 0.8	1.5 ± 0.8
	RSV/IL-4	23.0 ± 2.0	40.0 ± 7.6	0 (<0.001)	1.00 ± 0.67
	Mock	20.0 ± 5.0	5.0 ± 0	15.0 ± 5.6	5.0 ± 0

^aGroups of mice were infected on day 0 with wt RSV or RSV/IL-4 (9 or 10 animals per group per day) or were mock infected (4 animals per group per day). Animals were sacrificed on days 4 and 8 postinfection, and the lungs were removed for histopathologic analysis. The remaining animals (including the mock controls) were challenged on day 28 with wt RSV and then sacrificed on days 32 and 36 (4 or 8 days postchallenge, respectively), and the lungs were removed for histopathologic analysis.

^bAll groups are designated according to the inoculum on day 0.

^cScoring was done on a semiquantitative scale from 0 (no inflammation) to 100 (maximum). Peribronchiolitis, accumulation of inflammatory cells, primarily lymphocytes, surrounding a bronchiole; perivasculitis, inflammatory cells surrounding a blood vessel; interstitial pneumonitis, increased thickness of alveolar walls associated with inflammatory cells, primarily neutrophils; alveolitis, inflammatory cells, primarily neutrophils, within alveolar spaces.

^dStatistical significances of differences between the RSV/IL-4 and the wt RSV groups are shown in bold for P values of <0.05.