IFIH1 and viral infectious disease: Titration of MDA5 expression showed either a low or high dose of human LGP2 elicits a significant and sustainable promotion on MDA5 signaling in mammalian cells when transfected by poly(I:C) only at a low concentration (4 ng/ml) and instead, LGP2-mediated inhibition is easily detected at a high concentration (2 μg/ml) of poly(I:C) particularly when LGP2 is transfected at high dose of 200 ng (Figures 7I vs. 7H), thereby indicating that human LGP2 acts as an activator mainly at the early stage of viral infection.