Amyloodiniosis is caused by the dinoflagellate Amyloodinium ocellatum. It represents a critical challenge in marine aquaculture. In this study, we developed and evaluated the results of a vaccine composed of sonicated and frozen tomonts of A. ocellatum in mullet Mugil liza, a native Brazilian species with high cultivation potential.
The experiment was carried out using 90 juvenile mullets, with two treatments: Vaccine Treatment (VT) performed in triplicate, with 15 animals/tank; and Control Treatment (CT) in triplicate, with 15 animals/tank. In the study, juvenile of M. liza received intraperitoneal injections containing 1500 tomonts/mL. After a 15-day period, vaccinated and control groups were challenged with A. ocellatum tomonts (10/mL). Water quality parameters were rigorously maintained to ensure controlled conditions during all the experiment.
The vaccinated group demonstrated a survival rate of 97.73%, while the control group exhibited only 20% survival. The histopathologycal analyses showed that gills of the vaccinated fish had normal morphology, while the fish in the control group exhibited histopathological changes of moderate to severe hyperplasia in the proximal and distal lamellae, rupture of pillar cells and necrosis. These results indicate that vaccination with A. ocellatum tomonts treated by sonication and freezing was effective.
The findings demonstrate that immunization was effective in preventing pathological damage and mortality, underscoring the vaccine’s potential as a health management tool for marine aquaculture. The study provides the first robust evidence of successful vaccination against A. ocellatum in M. liza and suggests its broader application in preventing epizootics in cultured marine fish. Continued research should explore antigen concentration optimization, immune response characterization, and large-scale field application to support sustainable aquaculture development.
Vaccine (Tomont Antigen) ➝ IP Injection ➝ Immune Priming ➝ Challenge ➝ High Survival