The authors thank A. Sewell and G. Dolton (Cardiff, UK) for the generous provision of influenza M1-specific tetramers and initial influenza M1-specific CD8+ responder cell lines, M. Luo (Birmingham, AL, USA) for the influenza M1 expressing DNA plasmid, H. Jomaa (Giessen, Germany) for HMBPP, P. Lehner (Cambridge, UK) for KBM7 cells, and R. Pardi (Milano, Italy) for the anti-CD18 antibody. This evidence concerns the gene CD8A and influenza.