Although hemagglutinin (HA) from H5N1, but not H1N1, influenza is found to directly trigger γδ T cells to produce IFN-γ by binding to sialic acid receptors on the cells7, many γδ T cells utilize a relatively limited repertoire to recognize nonpeptide antigens and stress-induced ligands presented upon the major-histocompatibility-complex (MHC)-class-I-like molecule CD1d18,19. This evidence concerns the gene IFNG and influenza.