A Serum Cytotoxicity Assay for Measuring the Resistance of Turbot to the Ciliate Philasterides Dicentrarchi

Abstract

In 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 cytotoxicity activity in serum from the fish were compared. We found a good 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 evaluate 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 infection

Keywords: Philasterides dicentrarchi, fish, complement system, cytotoxicity, immunization, disease resistance