Non‐Coding Transcripts From Diversified Members of IgLec Family Protect Antiviral Effectors From Viral miRNA

ABSTRACT

Immune gene families frequently produce numerous non‐coding transcripts, yet their biological functions remain largely unexplored. Here, using the arthropod immunoglobulin domain‐containing lectin ( IgLec ) family as a paradigm, we provide evidence that this complexity may reflect a critical defensive function for non‐coding transcripts in antiviral immunity. IgLec is restricted to decapod infraorders (Brachyura and Astacidea), and a structurally related bacterial homolog suggests its origin may involve horizontal gene transfer. The IgLec family generates extraordinary transcript diversity through three mechanisms, multi‐locus duplication, inter‐locus recombination, and extensive alternative splicing, yielding both protein‐coding and non‐coding transcripts. Protein‐coding IgLec variants restrict viral replication by inducing antimicrobial peptide expression. Upon white spot syndrome virus infection, non‐coding transcripts (e.g., intron‐retaining transcripts) are preferentially targeted by virus‐encoded microRNA‐N48, thereby protecting protein‐coding isoforms from repression. Loss of these decoy transcripts compromises antiviral defense and increases host mortality. Collectively, these results reveal a decoy‐based antiviral strategy in which non‐coding transcripts safeguard immune effectors from pathogen subversion, uncovering an unrecognized layer of innate immunity.