TLR3 and avian influenza: In contrast, TLR3-deficient mice have been shown to be more susceptible to highly pathogenic avian influenza (HPAI) H5N1 infection [34], but are surprisingly protected from A/Scotland/20/74 (H3N2) and 2009 pandemic H1N1 infection [34,35], suggesting that the contribution of TLR3 responses to IAV infection may vary amongst strains.