Vaccine Development Against Amyloodinium ocellatum and Immunization of Mullet Mugil lizaAuthor: Luana Bortolini Giesta (Currículo Lattes)
Advisor: Dr. Luis Alberto Romano
Abstract
The mullet Mugil liza is the main species of the Mugilidae family targeted by commercial fishing along the Brazilian coast. Currently, its population is in decline due to the overexploitation of natural stocks. Aquaculture has emerged as an alternative to reduce pressure on wild populations. In this context, several studies have been conducted to make the captive production of M. liza feasible. Among the main diseases affecting marine fish production systems, amyloodiniosis stands out. It is caused by the dinoflagellate Amyloodinium ocellatum, a parasite responsible for infections that lead to high mortality rates in fish. The parasite’s three-phase life cycle makes effective control and disease prevention challenging. Immunization of fish against the parasite appears to be a promising approach for preventing amyloodiniosis. The objective of the present study was to develop a vaccine against A. ocellatum for M. liza. The vaccine was administered via intraperitoneal injection, and the fish were subsequently challenged with A. ocellatum tomonts. The results showed a significantly higher survival rate in vaccinated fish, with 97.73% survival in the vaccinated group compared to only 20% in the control group. Histopathological analysis revealed that the gills of vaccinated fish maintained normal morphology, whereas the control group displayed moderate to severe histopathological changes, including hyperplasia of proximal and distal lamellae, rupture of pillar cells, and necrosis. These findings indicate that vaccination using sonicated and frozen Amyloodinium ocellatum tomonts was effective in inducing a high survival rate in fish, suggesting its potential for use in immunizing M. liza against amyloodiniosis.