Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2018 Mar 16;10(3):133.
doi: 10.3390/v10030133.

Antiviral Defense and Innate Immune Memory in the Oyster

Timothy J Green  1   2 , Peter Speck  3
Affiliations
Review

Antiviral Defense and Innate Immune Memory in the Oyster

Timothy J Green et al. Viruses. .

Abstract

The Pacific oyster, Crassostrea gigas, is becoming a valuable model for investigating antiviral defense in the Lophotrochozoa superphylum. In the past five years, improvements to laboratory-based experimental infection protocols using Ostreid herpesvirus I (OsHV-1) from naturally infected C. gigas combined with next-generation sequencing techniques has revealed that oysters have a complex antiviral response involving the activation of all major innate immune pathways. Experimental evidence indicates C. gigas utilizes an interferon-like response to limit OsHV-1 replication and spread. Oysters injected with a viral mimic (polyI:C) develop resistance to OsHV-1. Improved survival following polyI:C injection was found later in life (within-generational immune priming) and in the next generation (multi-generational immune priming). These studies indicate that the oyster's antiviral defense system exhibits a form of innate immune-memory. An important priority is to identify the molecular mechanisms responsible for this phenomenon. This knowledge will motivate the development of practical and cost-effective treatments for improving oyster health in aquaculture.

Keywords: Crassostrea; OsHV-1; RNAi; immune priming; interferon.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Conceptual diagram of the interferon-like antiviral response of Crassostrea gigas involving the TLR/NF-κB, RIG-1/MAVS, and putative cGAS/STING signaling pathways that result in the transcription of antiviral genes. The oyster genome encodes several novel toll-like receptors (TLRs) that lack transmembrane domains, implying they have a cytoplasmic function. These novel TLRs and downstream signaling adaptors are upregulated in response to OsHV-1 inoculation [34,36,52]. The oyster has a functional RIG-1 pathway that senses the presence of cytoplasmic dsRNA (i.e., polyI:C) and signals via downstream MAVS and TRAF adaptors [46]. The transcription factor IRF appears to function downstream of oyster MAVS and activates the IFN promoter and IFN stimulated response elements (ISRE) in mammalian cells [46,53]. Activation of IRF and NF-κB results in their translocation to the cell nucleus, leading to the transcription of antiviral genes. It is not currently known if oysters have a functional cGAS/STING-dependent antiviral response (pathway highlighted with grey arrows) [54]. The oyster genome encodes a STING homologue with three N-terminal transmembrane domains followed by a STING domain [10]. Oyster STING binds cyclic dinucleotides (CDNs) [55] and interacts with downstream TBK1 kinase [39]. Functional assays are required to determine if oyster cGAS binds cytosolic DNA and synthesizes CDNs. Note the unusual protein domains for RIG-like receptors and STING. Novel RIG-like receptors contain N-terminal death domains and novel STING either lack transmembrane domains or contain TIR domains [56]. TIR domain-containing proteins such as TLRs and interleukin-1 receptors are known to play key roles in innate immune signaling [57]. TLR, toll-like receptor; MyD88, myeloid differentiation primary response 88; IRAK, interleukin receptor-associated kinase; TRAF, TNF-receptor associated factor; IKK, IκB kinase; IκB, Inhibitor of κB; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells; RIG-1, retinoic acid-inducible gene-1-like receptor; MAVS, mitochondria antiviral signaling protein; IFN, interferon; IRF, interferon regulatory factor; cGAS, cyclic GMP-AMP synthase; STING, stimulator of IFN genes; TBK1, tank binding kinase 1; STAT, signal transducer and activator of transcription; SOCS, suppressor of cytokine signaling; ISRE, IFN stimulated response element.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Escoubas J.-M., Destoumieux-Garzon D., Montagnani C., Gourbal B., Duval D., Green T.J., Charriere G.M. Immunity in Molluscs. In: Ratcliffe M.J.H., editor. Encyclopedia of Immunobiology. Academic Press; Oxford, UK: 2016. pp. 417–436.
    1. Bickham U., Bayne C.J. Molluscan cells in culture: Primary cell cultures and cell lines. Can. J. Zool. 2013;91:391–404. - PMC - PubMed
    1. Davison A.J., Eberia R., Ehlers B., Hayward G.S., McGeoch D.J., Minson A.C., Pellet P.E., Roizman B., Studdert M.J., Thiry E. The Order Herpesvirales. Arch. Virol. 2009;154:171–177. doi: 10.1007/s00705-008-0278-4. - DOI - PMC - PubMed
    1. Segarra A., Pepin J.F., Arzul I., Morga B., Faury N., Renault T. Detection and Description of a Particular Ostreid Herpesvirus 1 Genotype Associated with Massive Mortality Outbreaks of Pacific oysters, Crassostrea gigas, in France in 2008. Virus Res. 2010;153:92–99. doi: 10.1016/j.virusres.2010.07.011. - DOI - PubMed
    1. Jenkins C., Hick P., Gabor M., Spiers Z., Fell S.A., Gu X., Read A., Go J., Dove M., O’Connor W., et al. Identification and Characterisation of an Ostreid Herpesvirus-1 Microvariant (OsHV-1 μ-Var) in Crassostrea gigas (Pacific Oysters) in Australia. Dis. Aquat. Org. 2013;105:109–126. doi: 10.3354/dao02623. - DOI - PubMed

Publication types

LinkOut - more resources