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  • In vivo assessment of recombinant antibodies against Nervous Necrosis Virus (NNV) in European seabass (Dicentrarchus labrax)
    Publication . Batista, Henrique da Cruz; Baptista, Teresa Maria Coelho
    Viral nervous necrosis (VNN) is one of the most significant diseases in aquaculture, mainly affecting larvae and juveniles of several fish species, including the European sea bass (Dicentrarchus labrax), and it’s associated with high mortality rates and substantial economic losses. This study aimed to evaluate the effect of oral administration of recombinant antibodies (Ccombodies) on the immune response of juvenile sea bass experimentally infected with nervous necrosis virus (NNV). In a preliminary LD50 trial, both viral doses tested (105 and 106 TCID50/fish) resulted in 50% mortality at 5 days post-infection, accompanied by typical VNN clinical signs such as loss of orientation, spiral swimming, hyperactivity and anorexia. Due to the similarity of results the lowest dose was selected for the main trial. The passive immunization trial included four treatments: feed without antibodies (control) and feed supplemented with 1, 10 and 100 mg Ccombodies/100g diet. Cumulative mortality ranged from 36.6% (control) to 53.3% (10mg/100g), with no statistically significant differences between groups (p>0.05). Clinical signs were similar across treatments, suggesting that oral administration of recombinant antibodies did not provide effective protection against NNV. Enzymatic degradation in the digestive tract and dispersion of antibodies in the water may have compromised efficacy. In conclusion, under the tested conditions, recombinant antibodies did not confer significant protection against NNV infection in juvenile European sea bass. Future studies should explore alternative delivery strategies, such as microencapsulation, to enhance stability and improve the effectiveness of oral antibody administration. It is also essential in future studies to review the development of antibodies so that they confer protection against the virus.
    2025-11-26Dissertação de mestrado Acesso aberto Ver mais