Blood Transcriptomics of Turbot Scophthalmus maximus: A Tool for Health Monitoring and Disease Studies

Article with suplementary materials: The following are available online at https://www.mdpi.com/article/10.3390/ani11051296/s1 Publicly available datasets were analyzed in this study. Raw sequencing data have been deposited in NCBI’s Short Read Archive (SRA) under BioProject ID PRJNA70378Blood transcriptomics is emerging as a relevant tool to monitor the status of the immune system and assist in diagnosis, prognosis, treatment and pathogenesis studies of diseases. In fish pathology, the potential of transcriptome profiling of blood is still poorly explored. Here, RNA sequencing was applied to analyze the blood transcriptional profile of turbot (Scophthalmus maximus), the most important farmed flatfish. The study was conducted in healthy specimens and specimens parasitized by the myxozoan Enteromyxum scophthalmi, which causes one of the most devastating diseases in turbot aquaculture. The blood of healthy turbot showed a transcriptomic profile mainly related to erythrocyte gas transportation function, but also to antigen processing and presentation. In moderately infected turbot, the blood reflected a broad inhibition of the immune response. Particularly, down-regulation of the B cell receptor signaling pathway was shared with heavily parasitized fish, which showed larger transcriptomic changes, including the activation of the inflammatory response. Turbot response to enteromyxosis proved to be delayed, dysregulated and ineffective in stopping the infection. The study evinces that blood transcriptomics can contribute to a better understanding of the teleost immune system and serve as a reliable tool to investigate the physiopathological status of fish.This research was funded by the spanish ministry of economy, industry and competitiveness and the European Regional Development Fund (ERDF), grant number AGL2015–67039–C3–1–R and AGL2015–67039–C3–3–R. The study was conducted in accordance with national (Royal Decree RD53/2013) and European Union (Directive 2010/63/EU) regulation of the on the protection of animals used for scientific purposes and approved by the Ethics Committee of UNIVERDIDADE DE SANTIAGO DE COMPOSTELA (22 November 2016, code: ES1507730055401/16/INV.MED.02/ROD 02) The authors would like to thank Lucía Insua for technical assistance and they acknowledge the support of the Centro de Supercomputación de Galicia (CESGA) in the completion of this work.S