Molecular cloning and characterization of Toll-like receptor 3 in Japanese flounder, Paralichthys olivaceus

► We cloned the Japanese flounder TLR3 (JfTLR3) gene. ► Gene expression of JfTLR3 was up-regulated in PBLs after stimulation with poly I:C and CpG ODN 1668. ► JfTLR3 gene was induced in different tissues following infection with VHSV. ► Intracellular poly I:C in JfTLR3-overexpressing YO-K cells activates IFN and NF-κB pathways. ► In JfTLR3-overexpressing HINAE cells, extracellular poly I:C activates IFN and NF-κB pathways.