Characterisation and bioactivities of type I interferon subtype E and F in salmonids

Abstract

Salmonids are important commercial species in the European aquaculture industry. Many viral diseases can impact on the industry, leading to economic losses. Interferons (IFNs) are cytokines involved in antiviral defence, and study of their regulation and function may shed light on how fish can defend themselves against viral infection. Fish type I IFNs are classified into two groups based on cysteine residues in the mature peptide, namely group I and II IFNs, each of which is further divided into 3 subtypes in salmonids. The latest new subtypes, IFN-e and IFN-f, have only recently been identified and their biological activities have still to be characterised. In this presentation, IFN-e and –f genes in Atlantic salmon (Salmo salar) and their bioactivities were reviewed and compared to previous studies of other type I IFN subtypes (a-d). The type I IFN subtypes showed different expression patterns between the 2 groups in cell lines and primary head kidney cells stimulated with poly I:C and in heart and head kidney of cardiomyopathy syndrome (CMS) infected salmon. Transcript levels could be correlated to the antiviral response and the IFN-e and IFN–f recombinant proteins were shown to induce Mx gene expression which is known to mediate antiviral activity. This data together with the reactivity of specific antibodies to the subtypes provides a better understanding of the antiviral effects of type I IFNs in salmonids.