Characterization and expression analysis of laboratory of genetics and physiology 2 gene in sea perch, Lateolabrax japonicus

•The first LGP2 was identified from fish sea perch.•LjLGP2 transcripts were constitutively expressed in all examined tissues.•LjLGP2 transcripts were induced greatly in immune and non-immune organs post NNV infection in vivo.•LjLGP2 involved in response to poly(I:C) stimulation and NNV infection in vitro.

LGP2 (laboratory of genetics and physiology 2) as a key component of the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), plays a predominant role in modulating RLRs-mediated cellular antiviral signaling during viral infection. In the present study, we cloned the LGP2 gene from the sea perch (Lateolabrax japonicus) (LjLGP2), an economically important farmed fish. The complete cDNA sequence of LjLGP2 was 2790 nt and encoded a polypeptide of 682 amino acids which contains four main structural domains: one DEAD/DEAH box helicase domain, one conserved restriction domain of bacterial type III restriction enzyme, one helicase superfamily c-terminal domain and one C-terminal domain of RIG-I, similar to most vertebrate LGP2. Subcellular localization analysis showed that LjLGP2 spanned the entire cytosol. The LjLGP2 mRNA was widespread expressed in the tested 10 tissues of healthy fish and significantly up-regulated post NNV infection. Furthermore, time course analysis showed that LjLGP2 transcripts significantly increased in the spleen, kidney and liver tissues after NNV infection. LjLGP2 mRNA expression was rapidly and significantly up-regulated in LJB cells after poly I:C stimulation and NNV infection. The present results suggest that LjLGP2 may be involved in recognization of NNV and play a role in antiviral innate immune against NNV in sea perch.