OsHV-1 countermeasures to the Pacific oyster's anti-viral response

• Published in: Fish & Shellfish Immunology
• Main Authors: Green, Timothy, Rolland, Jean-Luc, Vergnes, Agnès, Raftos, David, Montagnani, Caroline
• Other Authors: University of Sydney Institute of Marine Science (USIMS), The University of Sydney, Dpt Biological Sciences, Macquarie University, Macquarie University, Interactions Hôtes-Pathogènes-Environnements (IHPE), Université de Perpignan Via Domitia (UPVD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Anti-viral response; Apoptosis; Crassostrea; Interferon-like; Poly I:C; [SDV.BID.EVO]Life Sciences [q-bio]/Biodiversity/Populations and Evolution [q-bio.PE]; Pacific; Crassostrea gigas; Pacific oyster
• Online Access: https://hal.science/hal-01260118; https://hal.science/hal-01260118/document; https://hal.science/hal-01260118/file/Green-2015-FishShelfImmunol-OSHV-1.pdf; https://doi.org/10.1016/j.fsi.2015.09.025

International audience The hostepathogen interactions between the Pacific oyster (Crassostrea gigas) and Ostreid herpesvirus type 1 (OsHV-1) are poorly characterised. Herpesviruses are a group of large, DNA viruses that are known to encode gene products that subvert their host's antiviral response. It is likely that OsHV-1 has also evolved similar strategies as its genome encodes genes with high homology to C. gigas inhibitors of apoptosis (IAPs) and an interferon-stimulated gene (termed CH25H). The first objective of this study was to simultaneously investigate the expression of C. gigas and OsHV-1 genes that share high sequence homology during an acute infection. Comparison of apoptosis-related genes revealed that components of the extrinsic apoptosis pathway (TNF) were induced in response to OsHV-1 infection, but we failed to observe evidence of apoptosis using a combination of biochemical and molecular assays. IAPs encoded by OsHV-1 were highly expressed during the acute stage of infection and may explain why we didn't observe evidence of apoptosis. However, C. gigas must have an alternative mechanism to apoptosis for clearing OsHV-1 from infected gill cells as we observed a reduction in viral DNA between 27 and 54 h post-infection. The reduction of viral DNA in C. gigas gill cells occurred after the up-regulation of interferon-stimulated genes (viperin, PKR, ADAR). In a second objective, we manipulated the host's antiviral response by injecting C. gigas with a small dose of poly I:C at the time of OsHV-1 infection. This small dose of poly I:C was unable to induce transcription of known antiviral effectors (ISGs), but these oysters were still capable of inhibiting OsHV-1 replication. This result suggests dsRNA induces an antiviral response that is additional to the IFN-like pathway