Fig 1.

Role of pulmonary macrophages in restricting RSV replication in naïve mice in the restriction of RSV replication in vivo by RSV-specific antibodies and in the alleviation of that restriction by sG expressed by wt RSV. The plan of each experiment is shown on the left, and the results are shown on the right. (A) Pulmonary macrophages, but not natural antibodies, restrict pulmonary RSV replication in RSV-naïve mice. Groups of mice (B, BALB/c; J, JHD; 4 animals per group, except for 5 in group B) were treated intranasally with clodronate to deplete pulmonary macrophages or mock treated, treated with normal BALB/c serum or control serum, and infected with mG RSV. The animals were sacrificed on day 4, and the pulmonary RSV titers were determined (PFU per gram of lung tissue [PFU/g], mean ± standard error [SE]). Statistical significance by Student's unpaired t test: groups AB, AE, BC, BD, BE, CE, and DE, P < 0.001; groups AC, P = 0.003; groups AD, P = 0.026. (B) Pulmonary macrophages are involved in the restriction of RSV replication by RSV-specific antibodies and in the alleviation of that restriction by sG expressed by wt RSV. BALB/c mice in groups of 5 were treated with clodronate or mock treated, treated with RSV F-specific antiserum or PBS, and infected with mG or wt RSV. The animals were sacrificed on day 4, and the pulmonary RSV titers were determined. Statistical significance: groups AC, BD, CE, and DF, P < 0.001; group BF, P = 0.010. The experiment shown in panel B was performed three times with similar results.