CAM was added to monolayers of A549 cells 1 h prior to RSV infection. The A549 cells infected with RSV at an MOI of 1 for 24 h and uninfected A549 cells were incubated with FITC-labeled S. pneumoniae cells at MOI of 10 for 30 min at 37 • C. For the control experiments, either 20 μg/mL of the PAF receptor antagonist or 10 μg/mL of the mouse anti-PAF receptor monoclonal antibody (11A4(clone 21)) was added to the A549 cells 1 h prior to the addition of the FITC-labeled bacteria. The cell monolayer was gently washed three times with PBS (−) and observed by fluorescence microscopy. Alternatively, the cells were harvested with cell scraper and then assessed by flow cytometry as previously described [26] .