title: Poly I:C induces a protective antiviral immune response in the Pacific oyster (Crassostrea gigas) against subsequent challenge with Ostreid herpesvirus (OsHV-1 μvar).
abstract: In-vivo studies were carried out to investigate the protective effect of a synthetic viral analogue (poly I:C) against Ostreid herpes virus (OsHV-1 μvar). Pacific oysters (Crassostrea gigas) were immune-primed by intramuscular injection of 240 μg of poly I:C or sterile seawater at 1 day prior to infection with OsHV-1 μvar. Poly I:C injection induced an antiviral state in C. gigas as the percentage of viral-infected oysters at 48 h post infection was significantly lower in the poly I:C treatment (11%) compared to seawater controls (100%). In an additional experiment, we demonstrated that the protective role of poly I:C is reproducible and elicits a specific antiviral response as immune-priming with heat-killed Vibrio splendidus provided no protection against subsequent viral infection. In both experiments, genes homologous to a toll-like receptor (TLR), MyD88, interferon regulatory factor (IRF) and protein kinase R (PKR) were up-regulated in oysters immune-primed with poly I:C compared to seawater controls (p < 0.05). The MyD88, IRF and PKR genes were also significantly up-regulated in response to OsHV-1 μvar infection (p < 0.05), which is suggestive that they are implicated in the antiviral response of C. gigas. Our results demonstrate that C. gigas can recognise double-strand RNA to initiate an innate immune response that inhibits viral infection. The observed response has striking similarities to the hallmarks of the type-1 interferon response of vertebrates.
authors.affiliation: Ifremer, UMR 5119 "Ecology of Coastal Marine Systems", Université Montpellier 2, Place Eugène Bataillon, CC80, 30495 Montpellier Cedex 05, France. Tim.Green@flinders.edu.au
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Green
authors.forename: Caroline
authors.initials: C
authors.lastname: Montagnani
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000276:immunology / Q000378:metabolism; D049896:Crassostrea / Q000235:genetics* / Q000276:immunology* / Q000821:virology; D005786:Gene Expression Regulation; D006564:Herpesviridae / Q000502:physiology*; D007113:Immunity, Innate; D007274:Injections, Intraperitoneal / Q000662:veterinary; D011070:Poly I-C / Q000494:pharmacology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D014733:Vibrio / Q000502:physiology
chemical_list: D000998:Antiviral Agents; D011070:Poly I-C
keywords: Crassostrea gigas; Interferon-like response; OsHV-1; Poly I:C; Vibrio splendidus