Some studies have shown that IL-6 knockout mice exhibit similar morbidity and mortality to wild-type mice when infected with highly pathogenic H5N1 influenza virus (Salomon et al., 2007; Szretter et al., 2007).These discrepancies may arise from differences in influenza strain, experimental conditions, or other variables, suggesting a need for further investigation with more rigorous and controlled experimental designs. This evidence concerns the gene IL6 and influenza.