Gulías Otero, PaolaSueiro Benavides, Rosa AnaGonzález Barreiro, ÓscarBrea Portela, CristinaMacías Sancho, JoaquínLeiro Vidal, José ManuelLamas Fernández, Jesús2025-12-152025-12-152025-10-30Guliás P, Sueiro RA, González O, Brea C, Macías J, Leiro JM, Lamas J. (2025). A serum cytotoxicity assay for measuring the resistance of turbot to the ciliate Philasterides dicentrarchi. Comparative Immunology Reports 9 (2025), 200259. doi: https://doi.org/10.1016/j.cirep.2025.2002592950-3116https://hdl.handle.net/10347/44491In previous studies we have found that the complement system plays an essential role in the resistance of fish to infection by the ciliate parasite Philasterides dicentrarchi. The present study shows that it is possible to predict resistance to P. dicentrarchi in the turbot Scophthalmus maximus by using a complement-dependent serum cytotoxicity assay. Fish were immunised against P. dicentrarchi, and fish mortality following experimental challenge, specific serum antibody levels and serum cytotoxicity were compared. We found a correlation between the results obtained regarding the killing activity of serum and the protection generated in turbot by the vaccine after experimental challenge. The study findings suggest that the serum cytotoxicity assay can be used to assess the protection generated by the vaccine against P. dicentrarchi in turbot, thereby reducing both the number of fish required for the experiments and the pain and distress associated with experimental infectioneng© 2025 The Authors. Published by Elsevier Ltd. This article is available under the Creative Commons CC-BY-NC-ND licensehttp://creativecommons.org/licenses/by-nc-nd/4.0/Philasterides dicentrarchiFishComplement systemCytotoxicityImmunizationDisease resistanceInvestigaciónjournal article10.1016/j.cirep.2025.200259open access