Using RT-PCR, the increase in the expression of known fish anti-viral genes, was detected, including GCRV-induced gene 2 (gig2), interferon regulatory factor 1 (irf1), myxovirus (influenza) resistance A (mxa), and viperin (also known as radical S-adenosyl methionine domain containing 2, rsad2)41–44, in zebrafish embryos with the overexpression of IFN-υ (Fig. 2b and Supplementary Fig. 1a−d). Here, MX1 is linked to influenza.