Fish interferon-stimulated genes: The antiviral effectors

• Interferon stimulated genes (ISGs) can be antiviral effectors that limit viral infection.
• Many ISGs have been identified in mammals and their mechanisms of action have been studied.
• Some fish ISGs have been identified as antiviral effectors, but almost nothing is known of their antiviral mechanisms.

Type I interferons (IFN) are the cornerstone cytokine of innate antiviral immunity. In response to a viral infection, IFN signaling results in the expression of a diverse group of genes known as interferon-stimulated genes (ISGs). These ISGs are responsible for interfering with viral replication and infectivity, helping to limit viral infection within a cell. In mammals, many antiviral effector ISGs have been identified and the antiviral mechanisms are at least partially elucidated. In fish fewer ISGs have been identified and while there is evidence they limit viral infection, almost nothing is known of their respective antiviral mechanisms. This review discusses seven ISGs common to mammals and fish and three ISGs that are unique to fish. The lack of understanding regarding fish ISG's antiviral effector functions is highlighted and draws attention to the need for research in this aspect of aquatic innate immunity.