Vaccination and immune responses of European sea bass (Dicentrarchus labrax L.) against betanodavirus

Abstract This review summarizes the available knowledge on the immune defences of European sea bass against antigenic preparations derived from the viral encephalopathy and retinopathy virus (betanodavirus), which represents a major threat to the health of this fish species. The nodavirus is widely present and differentiates into several strains that infect invertebrates (in insects, alphanodavirus) and teleost fish, and thus may represent a great problem for farmed fish species. Many efforts have been directed to discovering new immunizations to induce protection in sea bass, especially at young stages, and these efforts have included employing diverse betanodavirus strains, antigen preparation, vaccination routes, and the addition of adjuvants and/or immunostimulants. The obtained results showed that inactivated preparations of betanodavirus that were administered intraperitoneally may induce both immune recognition and protection. Attempts at performing mucosal immunization by immersion and/or oral administration, which is a vaccination route that is highly preferred for sea bass, have shown intriguing results, and more studies are necessary for its improvement. Overall, the objective of identifying a reliable vaccine that also cross-protects against different genotypes or reassortant viruses for use in European sea bass against betanodavirus appears to be an attainable goal in the near future.