Six to eight week old NIH Swiss-Webster mice (Charles River) were used for viral challenges. For protection studies, mice were divided into groups of 20 mice (5 for virus lung titers, 15 for survival). For bronchoalveolar lavage assays, an additional 5 mice were added for each group. Six to eight week old C57BL/6 mice were used for gene expression analysis, 6 mice per condition. Mice were handled in accordance with protocols approved by the Institutional Animal Care and Use Committees of Baylor College of Medicine and The University of Texas-M.D. Anderson Cancer Center, and euthanized if distressed.