FPS reduction in RSV titer correlates with increased IFN-γ production. Two groups of mice were sensitized with OVA, and then prophylactically treated with FP, Sal or FPS prior to infection with RSV. Three days after infection, they were sacrificed. Homogenates of lungs from one group of mice were assayed for RSV titer, and BAL fluid from the second group was assayed for IFN-γ. Results are from one representative experiment of two.