MMP9 prevents RSV infectivity of human airway epithelial cells and mouse lungs.

<p>(A) SAE cells were treated with various concentrations of active and inactive human MMP9 and TCID₅₀ assays were performed 48 hours later. (B) RSV was treated with various concentrations of active and inactive MMP9 prior to infecting SAE cells. TCID₅₀ assays were performed to determine the quantity of virus following MMP9 treatment. * Represents a p value less than 0.05 comparing inactive to active MMP9 for each concentration. All comparisons were determined by student t-tests. (C) <i>Mmp9</i>^-/- mice and their FVB/NJ WT littermates were infected with 1x10⁶ pfu of RSV and animals were euthanized 1, 3, 5 and 7 dpi. Plaque assays and RSV N copy number, by qPCR (on 7 dpi), confirmed viral titers in lung tissue from all RSV-infected animals. Graphs are represented as mean ± S.E.M, with each measurement performed 3 times on 10 animals/group. Two-way ANOVA was used to compare the time-course curves and multiple comparisons were determined by the Bonferroni method (left panel). p value shown for qPCR (right panel) comparing both treatments connected by a line, determined by student t-tests.