Figure 1.

Schematic diagram of the study design for elastase and LPS (E/LPS) exposure and infection with respiratory syncytial virus (RSV). Mice were intranasally instilled with 1.2 U of elastase on Day 1 followed by 7 μg of LPS on Day 4; this treatment regimen was performed for 4 consecutive weeks. Mice repeatedly treated with PBS instead of E/LPS were used as controls. At 3 days after the last LPS or PBS instillation, mice were inoculated with RSV (10⁶ pfu) or vehicle (Mock) by intranasal instillation, and lung tissues were analyzed on Days 1, 4, 7, 10, and 14 after infection. Lung tissues for the mock-infected groups were analyzed on Day 14 postinfection. Arrows denote necropsy of mice.