Previous studies demonstrated that antibody-mediated inhibition of TRAIL signalling resulted in reduced viral clearance in a mouse model of IV pneumonia [40], and that CD8+ T cells utilize TRAIL to kill IV-infected alveolar epithelial cells in vivo[41], suggesting IV-induced TRAIL as important executor of cytotoxic T lymphocyte (CTL) responses. This evidence concerns the gene TNFSF10 and susceptibility to pneumonia measurement.