Genome-wide identification, characterization, and expression analysis of scavenger receptor genes in orange-spotted...

Scavenger receptors (SRs) are a diverse group of pattern recognition receptors that mediate innate immune defenses in teleosts, but their diversity and functional roles in Epinephelus coioides have not been fully characterized. Here, 13 SR genes were identified through genome-wide mining and classified into five subclasses (class A, B, F, H, L). Bioinformatic analysis, including exon-intron organization, motif composition, conserved domains and selection pressure analysis, revealed high intraclass conservation. Expression analysis under two distinct challenges - Vibrio harveyi infection and low-salinity stress - revealed that several SR genes, including EcSCARA5, EcSCARB1, and EcSCARF2, were significantly regulated in a time- and tissue-specific manner. Enrichment analyses indicated associations with membrane-related transport, lipid metabolism, and immune pathways, supporting their potential roles in stress adaptation. These findings enhance our understanding of SR function and provide a basis for immune-related strategies to improve fish health in aquaculture.