Poly I:C induces a protective antiviral immune response in the Pacific oyster (Crassostrea gigas) against subsequent challenge with Ostreid herpesvirus (OsHV-1 mu var)

• Published in: Fish & Shellfish Immunology
• Main Authors: Green, Timothy, Montagnani, Caroline
• Format: Article in Journal/Newspaper
• Language: English
• Published: Academic Press Ltd- Elsevier Science Ltd 2013
• Subjects: Crassostrea gigas; OsHV-1; Poly I:C; Vibrio splendidus; Interferon-like response; Pacific; Pacific oyster
• Online Access: https://archimer.ifremer.fr/doc/00152/26293/24739.pdf; https://doi.org/10.1016/j.fsi.2013.04.051; https://archimer.ifremer.fr/doc/00152/26293/

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 mu var). Pacific oysters (Crassostrea gigas) were immune-primed by intramuscular injection of 240 mu g of poly I:C or sterile seawater at 1 day prior to infection with OsHV-1 mu var. 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 mu var 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.