Consistent with the hypothesis that HA conformational stability can affect the timing of the endosomal fusion and may influence cytokine release in PBMCs, we found that destabilization of HA leads to reduced levels of mRNA for RIG-I and IL6. IFITM3 is a broadly-acting antiviral molecule (71) with known anti-influenza activity (72, 73) and therefore may shape the cytokine expression profile. Here, IL6 is linked to influenza.