In considering the potential capacity of PMED HA DNA vaccination to elicit cross-reactive T cell responses able to recognize HA proteins from shifted strains of virus, it is notable that the addition of the GM-CSF adjuvant increased T cell responses against regions of the A/New Caledonia/20/99 HA protein found to exhibit sequence homology with the HA protein of the H5N1 A/Vietnam/1203/04 avian strain of influenza. This evidence concerns the gene CSF2 and influenza.