CCR1 and infection: This was done by infecting MDDC (n = 6 donors) with rgHMPV, rgHRSV, or rgHPIV3, subjecting them to a secondary stimulation with the pro-inflammatory cytokine cocktail or LPS at 4 h post-infection, and using flow cytometry to analyze the cell surface expression of CCR1, 2, 5, and 7 in the GFP-positive versus the GFP-negative populations at 48 h post-infection (Fig. 6).