Comparative basal transcriptome profiles of the olfactory rosette and gills of Atlantic salmon (Salmo salar) unveil shared and distinct immunological features

The molecular repertoire of the mucosa-associated lymphoid tissue (MALT) in the olfactory rosette in most teleost fish is unknown. Here we present the basal transcriptome of the olfactory rosette of Atlantic salmon (Salmo salar). To investigate its mucosal immune features, we performed a comparative transcriptomic analysis with the gills, one of the most studied organs possessing MALT. Pathway enrichment revealed that cytokine-cytokine interaction and the neuroactive ligand-receptor interaction pathways were at the core of the shared similarity between the two organs. The immunological features of the two organs were further characterised by the overrepresentation of several immune-related pathways, particularly important for pathogen recognition. The immunological differences between the two organs were underlined with the differential regulation of markers for interleukins, extracellular matrix, antimicrobial peptides, and complement. The basal transcriptome of Atlantic salmon olfactory rosette is a valuable molecular toolbox that will advance our understanding of nasal immunity in teleost fish. •24,880 genes were found in common between the two mucosal organs.•Higher number of exclusive genes in the olfactory rosette (OR) than the gills.•Neuroactive ligand-receptor interaction and cytokine-cytokine-receptor interaction were enriched pathways in OR.•Overrepresentation analysis of shared genes unveiled enriched pathways relevant for immune signalling.•Differential regulation of markers for interleukins, extracellular matrix, antimicrobial peptides and complement was observed.