Ceratothoa oestroides (Cymothoidea, Isopoda) is a generalist crustacean parasite that negatively affects the economic sustainability of European sea bass (Dicentrarchus labrax) aquaculture in the North-East Mediterranean. While mortalities are observed in fry and fingerlings, infection in juvenile and adult fish result in approximately 20% growth delay. A transcriptomic analysis (PCR array, RNA-Seq) was performed on organs (tongue, spleen, head kidney, and liver) from infected vs. Ceratothoa-free sea bass fingerlings. Activation of local and systemic immune responses was detected, particularly in the spleen, characterized by the upregulation of cytokines (also in the tongue), a general reshaping of the immunoglobulin (Ig) response and suppression of T-cell mediated responses. Interestingly, starvation and iron transport and metabolism genes were strongly downregulated, suggesting that the parasite feeding strategy is not likely hematophagous. The regulation of genes related to growth impairment and starvation supported the growth delay observed in infected animals. Most differentially expressed (DE) transcripts were exclusive of a specific organ; however, only in the tongue, the difference between infected and uninfected fish was significant. At the attachment/feeding site, the pathways involved in muscle contraction and intercellular junction were the most upregulated, whereas the pathways involved in fibrosis (extracellular matrix organization, collagen formation, and biosynthesis) were downregulated. These results suggest that parasite-inflicted damage is successfully mitigated by the host and characterized by regenerative processes that prevail over the reparative ones.

Biology Centre of the Czech Academy of Sciences Institute of Parasitology Ceske Budejovice Czechia

Fish Pathology Group Institute of Aquaculture Torre de la Sal Consejo Superior de Investigaciones Científicas Castellón Spain

Future Genomics Technology Leiden Netherlands

Laboratory for Aquaculture Institute of Oceanography and Fisheries Split Croatia

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Shinn AP, Pratoomyot J, Bron JE, Paladini G, Brooker EE, Brooker AJ. Economic costs of protistan and metazoan parasites to global mariculture. Parasitology. (2015) 142:196–270. 10.1017/S0031182014001437 PubMed DOI

Misganaw K, Getu A. Review on major parasitic crustacean in fish. Fish Aquac J. (2016) 7:3. 10.4172/2150-3508.1000175 DOI

Brusca RC. A monograph on the isopoda cymothoidae (crustacea) of the eastern Pacific. Zool J Linn Soc. (1981) 73:117–99. 10.1111/j.1096-3642.1981.tb01592.x DOI

Papapanagiotou EP, Trilles JP. Cymothoid parasite Ceratothoa parallela inflicts great losses on cultured gilthead sea bream Sparus aurata in Greece. Dis Aquat Organ. (2001) 45:237–9. 10.3354/dao045237 PubMed DOI

Mladineo I. Prevalence of Ceratothoa oestroides (Risso, 1826), a cymothoid isopod parasite, in cultured sea bass Dicentrarchus labrax L. on two farms in middle Adriatic Sea. Acta Adriat. (2002) 43:97–102. 10.3354/dao057097 DOI

Colak S, Kolega M, MejdandŽić D, Župan I, Šarić T, Piplović E, et al. . Prevalence and effects of the cymothoid isopod (Ceratothoa oestroides, Risso 1816) on cultured meagre (Argyrosomus regius, Asso 1801) in the Eastern Adriatic Sea. Aquac Res. (2018) 49:1001–7. 10.1111/are.13547 DOI

Vagianou S, Athanassopoulou F, Ragias V, di Cave D, Leontidis L, Golomazou E. Prevalence and pathology of ectoparasites of Mediterranean fish, reared under three different environmental and aquaculture conditions in Greece. J Hell Vet Med Soc. (2004) 55:203–16. 10.12681/jhvms.15147 DOI

Šarušic G. Preliminary report of infestation by isopod Ceratothoa oestroides (Risso, 1826), in marine cultured fish. Bull Eur Assoc Fish Pathol. (1999) 19:110–112.

Horton T, Okamura B. Post-haemorrhagic anaemia in sea bass, Dicentrarchus labrax (L.), caused by blood feeding of Ceratothoa oestroides (Isopoda: cymothoidae). J Fish Dis. (2003) 26:401–6. 10.1046/j.1365-2761.2003.00476.x PubMed DOI

Horton T, Okamura B. Cymothoid isopod parasites in aquaculture: a review and case study of a Turkish sea bass (Dicentrarchus labrax) and sea bream (Sparus auratus) farm. Dis Aquat Organ. (2001) 46:181–8. 10.3354/dao046181 PubMed DOI

Günther K. Bau und funktion der mundwerkzeuge bei crustaceen aus der familie der cymothoidae (Isopoda). Zeitschrift für Morphol und Ökologie der Tiere. (1931) 23:1–79. 10.1007/978-3-662-31677-1_1 DOI

Nagler C, Haug JT. Functional morphology of parasitic isopods: understanding morphological adaptations of attachment and feeding structures in Nerocila as a pre-requisite for reconstructing the evolution of Cymothoidae. PeerJ. (2016) 4:e2188. 10.7717/peerj.2188 PubMed DOI PMC

Mladineo I, Hrabar J, Vidjak O, Bočina I, Colak S, Katharios P, et al. . Host-parasite interaction between parasitic Cymothoid Ceratothoa oestroides and its host, farmed European sea bass (Dicentrarchus labrax). Pathogens. (2020) 9:230. 10.3390/pathogens9030230 PubMed DOI PMC

Romestand B, Thuet P, Trilles J-P. Quelques aspects des mécanismes nutritionnels chez l'isopode cymothoidae: Ceratothoa oestroides (Risso, 1826). Ann Parasitol Hum Comp. (1982) 57:79–89. 10.1051/parasite/1982571079 PubMed DOI

Wang T, Mai K, Ai Q. A review of cyclooxygenase-2 role in fish. Austin J Nutr Metab. (2016) 3:1037. Available online at: https://austinpublishinggroup.com/nutrition-metabolism/fulltext/ajnm-v3-id1037.php

Mathews MB, Bernstein RM, Franza BR, Garrels JI. Identity of the proliferating cell nuclear antigen and cyclin. Nature. (1984) 309:374–6. 10.1038/309374a0 PubMed DOI

Piazzon MC, Mladineo I, Naya-Català F, Dirks RP, Jong-Raadsen S, Vrbatović A, et al. . Acting locally - affecting globally: RNA sequencing of gilthead sea bream with a mild Sparicotyle chrysophrii infection reveals effects on apoptosis, immune and hypoxia related genes. BMC Genomics. (2019) 20:200. 10.1186/s12864-019-5581-9 PubMed DOI PMC

Livak KJ, Schmittgen TD. Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method. Methods. (2001) 25:402–8. 10.1006/meth.2001.1262 PubMed DOI

Kim D, Langmead B, Salzberg SL. HISAT: a fast spliced aligner with low memory requirements. Nat Methods. (2015) 12:357–60. 10.1038/nmeth.3317 PubMed DOI PMC

Trapnell C, Williams BA, Pertea G, Mortazavi A, Kwan G, van Baren MJ, et al. . Transcript assembly and quantification by RNA-Seq reveals unannotated transcripts and isoform switching during cell differentiation. Nat Biotechnol. (2010) 28:511–5. 10.1038/nbt.1621 PubMed DOI PMC

Afgan E, Baker D, Batut B, van den Beek M, Bouvier D, Cech M, et al. . The Galaxy platform for accessible, reproducible, and collaborative biomedical analyses: 2018 update. Nucleic Acids Res. (2018) 46:W537–44. 10.1093/nar/gky379 PubMed DOI PMC

Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ. Basic local alignment search tool. J Mol Biol. (1990) 215:403–10. 10.1016/S0022-2836(05)80360-2 PubMed DOI

Trapnell C, Roberts A, Goff L, Pertea G, Kim D, Kelley DR, et al. . Differential gene and transcript expression analysis of RNA-seq experiments with TopHat and Cufflinks. Nat Protoc. (2012) 7:562–78. 10.1038/nprot.2012.016 PubMed DOI PMC

Love MI, Huber W, Anders S. Moderated estimation of fold change and dispersion for RNA-seq data with DESeq2. Genome Biol. (2014) 15:550. 10.1186/s13059-014-0550-8 PubMed DOI PMC

Eden E, Navon R, Steinfeld I, Lipson D, Yakhini Z. GOrilla: a tool for discovery and visualization of enriched GO terms in ranked gene lists. BMC Bioinformatics. (2009) 10:48. 10.1186/1471-2105-10-48 PubMed DOI PMC

Yu G, He Q-Y. ReactomePA: an R/Bioconductor package for reactome pathway analysis and visualization. Mol Biosyst. (2016) 12:477–9. 10.1039/C5MB00663E PubMed DOI

Fabregat A, Jupe S, Matthews L, Sidiropoulos K, Gillespie M, Garapati P, et al. . The reactome pathway knowledgebase. Nucleic Acids Res. (2018) 46:D649–55. 10.1093/nar/gkx1132 PubMed DOI PMC

Boyle EI, Weng S, Gollub J, Jin H, Botstein D, Cherry JM, et al. . GO::TermFinder-open source software for accessing gene ontology information and finding significantly enriched gene ontology terms associated with a list of genes. Bioinformatics. (2004) 20:3710–5. 10.1093/bioinformatics/bth456 PubMed DOI PMC

Kassambara A, Mundt F. Factoextra: Extract and Visualize the Results of Multivariate Data Analyses. (2017). Available online at: http://www.sthda.com/english/rpkgs/factoextra.

Smit NJ, Bruce NL, Hadfield KA. Global diversity of fish parasitic isopod crustaceans of the family Cymothoidae. Int J Parasitol Parasites Wildl. (2014) 3:188–97. 10.1016/j.ijppaw.2014.03.004 PubMed DOI PMC

Morton B. Host specificity and position on the host in Nerocila phaeopleura Bleeker (Isopoda, Cymothoidae). Crustaceana. (1974) 26:143–8. 10.1163/156854074X00505 DOI

Gintof C, Konow N, Ross CF, Sanford CPJ. Rhythmic chewing with oral jaws in teleost fishes: a comparison with amniotes. J Exp Biol. (2010) 213:1868–75. 10.1242/jeb.041012 PubMed DOI

Candi E, Schmidt R, Melino G. The cornified envelope: a model of cell death in the skin. Nat Rev Mol Cell Biol. (2005) 6:328–40. 10.1038/nrm1619 PubMed DOI

Litjens SHM, de Pereda JM, Sonnenberg A. Current insights into the formation and breakdown of hemidesmosomes. Trends Cell Biol. (2006) 16:376–83. 10.1016/j.tcb.2006.05.004 PubMed DOI

Allen JE, Maizels RM. Diversity and dialogue in immunity to helminths. Nat Rev Immunol. (2011) 11:375–88. 10.1038/nri2992 PubMed DOI

Hönzke S, Wallmeyer L, Ostrowski A, Radbruch M, Mundhenk L, Schäfer-Korting M, et al. . Influence of Th2 cytokines on the cornified envelope, tight junction proteins, and ß-defensins in filaggrin-deficient skin equivalents. J Invest Dermatol. (2016) 136:631–9. 10.1016/j.jid.2015.11.007 PubMed DOI

Rodrigues V, Cordeiro-da-Silva A, Laforge M, Ouaissi A, Akharid K, Silvestre R, et al. . Impairment of T cell function in parasitic infections. PLoS Negl Trop Dis. (2014) 8:e2567. 10.1371/journal.pntd.0002567 PubMed DOI PMC

Wynn TA. Cellular and molecular mechanisms of fibrosis. J Pathol. (2008) 214:199–210. 10.1002/path.2277 PubMed DOI PMC

Alfonso-Prieto M, Navarini L, Carloni P. Understanding ligand binding to G-protein coupled receptors using multiscale simulations. Front Mol Biosci. (2019) 6:29. 10.3389/fmolb.2019.00029 PubMed DOI PMC

Dessauer CW, Chen-Goodspeed M, Chen J. Mechanism of Galpha i-mediated inhibition of type V adenylyl cyclase. J Biol Chem. (2002) 277:28823–9. 10.1074/jbc.M203962200 PubMed DOI

Taylor SS, Kim C, Cheng CY, Brown SHJ, Wu J, Kannan N. Signaling through cAMP and cAMP-dependent protein kinase: diverse strategies for drug design. Biochim Biophys Acta. (2008) 1784:16–26. 10.1016/j.bbapap.2007.10.002 PubMed DOI PMC

Cao X, Dang W. Histone modification changes during aging: cause or consequence?—What we have learned about epigenetic regulation of aging from model organisms,. In. Moskalev A, Vaiserman A. editors. Translational Epigenetics Boston: Academic Press; (2018) p. 309–28. 10.1016/B978-0-12-811060-7.00015-2 DOI

Yu L, Zhang B, Deochand D, Sacta MA, Coppo M, Shang Y, et al. . Negative elongation factor complex enables macrophage inflammatory responses by controlling anti-inflammatory gene expression. Nat Commun. (2020) 11:2286. 10.1038/s41467-020-16209-5 PubMed DOI PMC

Yasinska IM, Meyer NH, Schlichtner S, Hussain R, Siligardi G, Casely-Hayford M, et al. . Ligand-receptor interactions of galectin-9 and VISTA suppress human T lymphocyte cytotoxic activity. Front Immunol. (2020) 11:3015. 10.3389/fimmu.2020.580557 PubMed DOI PMC

Takahashi M, Iwaki D, Kanno K, Ishida Y, Xiong J, Matsushita M, et al. . Mannose-binding lectin (MBL)-associated serine protease (MASP)-1 contributes to activation of the lectin complement pathway. J Immunol. (2008) 180:6132–8. 10.4049/jimmunol.180.9.6132 PubMed DOI

Gonzalez SF, Buchmann K, Nielsen ME. Complement expression in common carp (Cyprinus carpio L.) during infection with Ichthyophthirius multifiliis. Dev Comp Immunol. (2007) 31:576–86. 10.1016/j.dci.2006.08.010 PubMed DOI

Li M, Li J, Sun L. CsMAP34, a teleost MAP with dual role: a promoter of MASP-assisted complement activation and a regulator of immune cell activity. Sci Rep. (2016) 6:39287. 10.1038/srep39287 PubMed DOI PMC

Snykers S, Henkens T, De Rop E, Vinken M, Fraczek J, De Kock J, et al. . Role of epigenetics in liver-specific gene transcription, hepatocyte differentiation, and stem cell reprogrammation. J Hepatol. (2009) 51:187–211. 10.1016/j.jhep.2009.03.009 PubMed DOI

Sit S-T, Manser E. Rho GTPases and their role in organizing the actin cytoskeleton. J Cell Sci. (2011) 124:679–83. 10.1242/jcs.064964 PubMed DOI

Finkelman FD, Shea-Donohue T, Morris SC, Gildea L, Strait R, Madden KB, et al. . Interleukin-4- and interleukin-13-mediated host protection against intestinal nematode parasites. Immunol Rev. (2004) 201:139–55. 10.1111/j.0105-2896.2004.00192.x PubMed DOI

Nelms K, Keegan AD, Zamorano J, Ryan JJ, Paul WE. The IL-4 receptor: signaling mechanisms and biologic functions. Annu Rev Immunol. (1999) 17:701–38. 10.1146/annurev.immunol.17.1.701 PubMed DOI

Castro R, Jouneau L, Pham HP, Bouchez O, Giudicelli V, Lefranc MP, et al. . Teleost fish mount complex clonal IgM and IgT responses in spleen upon systemic viral infection. PLoS Pathog. (2013) 9:e1003098. 10.1371/journal.ppat.1003098 PubMed DOI PMC

Fillatreau S, Six A, Magadan S, Castro R, Sunyer JO, Boudinot P. The astonishing diversity of Ig classes and B cell repertoires in teleost fish. Front Immunol. (2013) 4:1–14. 10.3389/fimmu.2013.00028 PubMed DOI PMC

Abos B, Estensoro I, Perdiguero P, Faber M, Hu YF, Rosales PD, et al. . Dysregulation of B cell activity during proliferative kidney disease in rainbow trout. Front Immunol. (2018) 9:1203. 10.3389/fimmu.2018.01203 PubMed DOI PMC

Picard-Sánchez A, Estensoro I, Perdiguero P, del Pozo R, Tafalla C, Piazzon MC, et al. . Passive immunization delays disease outcome in gilthead sea bream infected with Enteromyxum leei (Myxozoa), despite the moderate changes in IgM and IgT repertoire. Front Immunol. (2020) 11:2242. 10.3389/fimmu.2020.581361 PubMed DOI PMC

Pan WW, Myers MGJ. Leptin and the maintenance of elevated body weight. Nat Rev Neurosci. (2018) 19:95–105. 10.1038/nrn.2017.168 PubMed DOI

Karra E, Chandarana K, Batterham RL. The role of peptide YY in appetite regulation and obesity. J Physiol. (2009) 587:19–25. 10.1113/jphysiol.2008.164269 PubMed DOI PMC

Benedito-Palos L, Saera-Vila A, Calduch-Giner JA, Kaushik S, Pérez-Sánchez J. Combined replacement of fish meal and oil in practical diets for fast growing juveniles of gilthead sea bream (Sparus aurata L.): networking of systemic and local components of GH/IGF axis. Aquaculture. (2007) 267:199–212. 10.1016/j.aquaculture.2007.01.011 DOI

Pérez-Sánchez J, Simó-Mirabet P, Naya-Català F, Martos-Sitcha JA, Perera E, Bermejo-Nogales A, et al. . Somatotropic axis regulation unravels the differential effects of nutritional and environmental factors in growth performance of marine farmed fishes. Front Endocrinol. (2018) 9:687. 10.3389/fendo.2018.00687 PubMed DOI PMC

Sitjà-Bobadilla A, Calduch-Giner J, Saera-Vila A, Palenzuela O, Álvarez-Pellitero P, Pérez-Sánchez J. Chronic exposure to the parasite Enteromyxum leei (Myxozoa: myxosporea) modulates the immune response and the expression of growth, redox, and immune relevant genes in gilthead sea bream, Sparus aurata L. Fish Shellfish Immunol. (2008) 24:610–9. 10.1016/j.fsi.2008.01.014 PubMed DOI

Calduch-Giner JA, Sitjà-Bobadilla A, Davey GC, Cairns MT, Kaushik S, Pérez-Sánchez J. Dietary vegetable oils do not alter the intestine transcriptome of gilthead sea bream (Sparus aurata), but modulate the transcriptomic response to infection with Enteromyxum leei. BMC Genomics. (2012) 13:470. 10.1186/1471-2164-13-470 PubMed DOI PMC

Nozzi V, Strofaldi S, Piquer IF, Di Crescenzo D, Olivotto I, Carnevali O. Amyloodinum ocellatum in Dicentrarchus labrax: study of infection in salt water and freshwater aquaponics. Fish Shellfish Immunol. (2016) 57:179–85. 10.1016/j.fsi.2016.07.036 PubMed DOI

Prospecting microbiota of Adriatic fish: Bacillus velezensis as a potential probiotic candidate

To React or Not to React: The Dilemma of Fish Immune Systems Facing Myxozoan Infections