FIG. 1.
Comparative effects of anti-RSV antibodies on RSV replication determined by quantitative culture of BAL samples and lung supernatant homogenates. Mice were intranasally inoculated with RSV (107.5 PFU/ml) or 10% EMEM (uninfected controls) and treated with a single dose of either palivizumab or MEDI-524 at one of several different time points. On days 1 and 5 after RSV inoculation, mice were sacrificed, and BAL and lung samples from the same mice were harvested (n = 8 to 16). The RSV loads in BAL samples (A) and both BAL samples and lung specimens (B) were determined by plaque assays. (A) The treatment groups consisted of uninfected controls, RSV-infected untreated mice, and RSV-infected mice receiving either palivizumab or MEDI-524 at either −24 h (before) or +48 h (after) with respect to RSV infection. (B) Viral load was significantly higher (P < 0.05) on day 5 in lung specimens than in BAL samples for RSV-infected untreated mice and mice that received palivizumab at −24 h or +48 h of RSV infection. The values are represented as median RSV log10 PFU/ml (with error bars indicating 25th to 75th percentiles) in BAL fluid (*, P < 0.001) or lung supernatant (‡, P < 0.001) by way of Kruskal-Wallis analysis of variance on ranks for comparison with RSV-infected untreated controls. VL, viral load; dashed line, lower limit of detection of the plaque assay.