A Sustained Immune Response Supports Long-Term Antiviral Immune Priming in the Pacific Oyster, Crassostrea gigas

TLDR

Innate immune memory has been observed in invertebrates, yet few molecular mechanisms have been identified to explain this phenomenon. The study aims to perform the first comprehensive transcriptomic analysis of antiviral innate immune priming in the Pacific oyster, *Crassostrea gigas*. Using poly(I·C) priming and transcriptomic profiling, the authors investigated the molecular basis of antiviral immune priming in the Pacific oyster. Poly(I·C) priming induced a sustained upregulation of immune genes that persisted for more than four months, supporting a long‑term antiviral priming mechanism and suggesting pseudovaccination strategies for invertebrates.

Abstract

In the last decade, important discoveries have shown that resistance to reinfection can be achieved without a functional adaptive immune system, introducing the concept of innate immune memory in invertebrates. However, this field has been constrained by the limited number of molecular mechanisms evidenced to support these phenomena. Taking advantage of an invertebrate species, the Pacific oyster ( Crassostrea gigas ), in which we evidenced one of the longest and most effective periods of protection against viral infection observed in an invertebrate, we provide the first comprehensive transcriptomic analysis of antiviral innate immune priming. We show that priming with poly(I·C) induced a massive upregulation of immune-related genes, which control subsequent viral infection, and it was maintained for over 4 months after priming. This acquired resistant mechanism reinforces the molecular foundations of the sustained response model of immune priming. It opens the way to pseudovaccination to prevent the recurrent diseases that currently afflict economically or ecologically important invertebrates.