title: Antiviral effects of β-defensin derived from orange-spotted grouper (Epinephelus coioides).
abstract: Defensins are a group of small antimicrobial peptides playing an important role in innate host defense. In this study, a β-defensin cloned from liver of orange-spotted grouper, Epinephelus coioides, EcDefensin, showed a key role in inhibiting the infection and replication of two kinds of newly emerging marine fish viruses, an enveloped DNA virus of Singapore grouper iridovirus (SGIV), and a non-enveloped RNA virus of viral nervous necrosis virus (VNNV). The expression profiles of EcDefensin were significantly (P < 0.001) up-regulated after challenging with Lipopolysaccharide (LPS), SGIV and Polyriboinosinic Polyribocytidylic Acid (polyI:C) in vivo. Immunofluorescence staining observed its intracellular innate immune response to viral infection of SGIV and VNNV. EcDefensin was found to possess dual antiviral activity, inhibiting the infection and replication of SGIV and VNNV and inducting a type I interferon-related response in vitro. Synthetic peptide of EcDefensin (Ec-defensin) incubated with virus or cells before infection reduced the viral infectivity. Ec-defensin drastically decreased SGIV and VNNV titers, viral gene expression and structural protein accumulation. Grouper spleen cells over-expressing EcDefensin (GS/pcDNA-EcDefensin) support the inhibition of viral infection and the upregulation of the expression of host immune-related genes, such as antiviral protein Mx and pro-inflammatory cytokine IL-1β. EcDefensin activated type I IFN and Interferon-sensitive response element (ISRE) in vitro. Reporter genes of IFN-Luc and ISRE-Luc were significantly up-regulated in cells transfected with pcDNA-EcDefenisn after infection with SGIV and VNNV. These results suggest that EcDefensin is importantly involved in host immune responses to invasion of viral pathogens, and open the new avenues for design of antiviral agents in fisheries industry.
authors.affiliation: Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, PR China.
authors.forename: Minglan
authors.initials: M
authors.lastname: Guo
authors.forename: Jingguang
authors.initials: J
authors.lastname: Wei
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Huang
authors.forename: Youhua
authors.initials: Y
authors.lastname: Huang
authors.forename: Qiwei
authors.initials: Q
authors.lastname: Qin
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D004266:DNA Virus Infections / Q000276:immunology / Q000662:veterinary; D004926:Escherichia coli / Q000378:metabolism; D005455:Fluorescent Antibody Technique / Q000662:veterinary; D020869:Gene Expression Profiling / Q000662:veterinary; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D007274:Injections, Intraperitoneal / Q000662:veterinary; D050835:Interferon Regulatory Factors / Q000378:metabolism; D007370:Interferon Type I / Q000378:metabolism; D017994:Iridovirus; D008070:Lipopolysaccharides / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D030381:Nodaviridae; D010473:Perciformes / Q000276:immunology* / Q000821:virology; D011070:Poly I-C / Q000378:metabolism; D012327:RNA Virus Infections / Q000276:immunology / Q000662:veterinary; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment / Q000662:veterinary; D017422:Sequence Analysis, DNA / Q000662:veterinary; D020539:Sequence Analysis, Protein / Q000662:veterinary; D023083:beta-Defensins / Q000737:chemistry / Q000276:immunology*
chemical_list: D050835:Interferon Regulatory Factors; D007370:Interferon Type I; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D023083:beta-Defensins; D008156:Luciferases; D011070:Poly I-C