Molecular cloning and immune responsive expression of LGP2 gene, a pivotal member of the RLR gene family from Muscovy duck Cairina moschata.

Laboratory of genetics and physiology 2 (LGP2) is an important intracellular receptor that recognizes viral RNAs in innate immunity. In this study, a novel LGP2 cDNA was identified from the spleen of a Muscovy duck (Cairina moschata). The deduced amino acid sequence of Muscovy duck LGP2 (MDLGP2) consisted of 675 amino acid residues. The peptide contained two main structure domains: six important motifs, including a DExD/H box for RNA helicase activity in the RNA helicase region located at the N-terminal region, and two Zn2+-binding regions with an RNA-binding loop in the C-terminus regulatory domain (CTD). The MdLGP2 mRNA was ubiquitously expressed in the tested tissues, with high expression levels in glandular stomach, colon, ileum, crop, and caecum tissues, and low expression levels in the brain, skin, and heart. The mRNA expression of MdLGP2 was significantly upregulated in the brain, spleen, and lungs of ducks in the early stages of postinfection with H5N1 highly pathogenic avian influenza virus (HPAIV). These results suggested that MdLGP2 was involved in the early stages of antiviral innate immune response in ducks after infection with H5N1 HPAIV. However, whether it plays a positive or negative regulatory role in the host antiviral response requires further investigation.