However, upon pulmonary infection with influenza virus, IFN-γ secreting CD8 T-cells can be detected only after 5 days in the lungs [35] whereas, after immunization with MVA-H1, they are present already in high frequencies before infection, and, upon infection, enter the lungs much more rapidly by relocation from other sites such as the spleen. This evidence concerns the gene CD8A and infection.