VACCINATION OF JUVENILE TURBOT, SCOPHTHALMUS-MAXIMUS L, AGAINST VIBRIOSIS

An intraperitoneal (IP) vaccination against vibriosis caused by Vibrio anguillarum 408 was carried out on four groups (I to IV) of juvenile turbot from the same origin at 62 (I), 76 (II), 90 (III) and 104 (IV) days post-hatching. The mean weight was 0.4 to 1.3 g. Intraperitoneal vaccination protected juvenile turbot during a challenge performed 1 month after a single immunization. The relative percentage survival (RPS) was about the same whether the vaccination occurred 62, 76 or 104 days post-hatching. Two months after this first immunization, juvenile turbot from groups III and IV were still protected and RPS values were higher than those obtained 1 month after vaccination. No booster effect was found in groups I and II. Although it was only significant in groups II and III, an increase of the spleen weight occurred in the vaccinated fish when compared to the controls. This was associated with a higher number of leucocytes per gram of organ. The immunization seemed to induce a mobilization of leucocytes in the spleen. Such results were not observed with the kidney.