Molecular and functional characterization of Viperin in large yellow croaker (Larimichthys crocea)

Viperin (virus inhibitory protein, endoplasmic reticulum-associated, interferon-inducible), also known as RSAD2 (radical SAM domain-containing 2), is one of the interferon-stimulated genes and plays an important role in cellular antiviral response. In this study, the viperin gene in large yellow croaker (Larimichthys crocea), designated LcViperin, was identified and characterized by investigating its tissue expression pattern and transcriptional response to viral infection and analyzing the differentially expressed genes (DEGs) upon overexpression of LcViperin in LCM10 cells revealed by RNA-seq transcriptome profiling. The results showed that LcViperin was highly expressed in the blood and organs of the immune system such as spleen and kidney, and the LcViperin protein was localized to the endoplasmic reticulum. The transcript level of LcViperin can be upregulated by large yellow croaker iridovirus (LYCIV) infection and the simulated viral infection of poly (I: C). GO and KEGG analysis of the DEGs demonstrated that the overexpression of LcViperin activated macrophage endocytosis pathway and other pathways to eliminate the viral particles. Flow cytometry analysis indicated an increase in macrophage phagocytotic activity and an induced respiratory burst in LCM10 cells upon exposure to LcViperin protein. The transcriptome analysis results would help to understand the host immune response and the potential mechanism of fish Viperin protein in response to pathogen stimulation.