TLR7 and viral infectious disease: In mice deficient in TLR7/9 or Myd88 or depleted of pDCs and infected with viruses, such as MCMV, HSV or DENV, NK cell cytotoxicity, and cytokine production were decreased or even abolished [21, 41, 70, 82, 92, 195], thus supporting the contribution of pDCs to NK cell activation in vivo during viral infections.