Evaluation of the efficacy of microencapsulatedscaffold against Edwardsiellatardain oral vaccinated Nile tilapia (Oreochromis niloticus)

Abstract

Edwardsiellatarda, a re-emerging pathogen, significantly impacts the productivity of marine and freshwater aquaculture by causing edwardsiellosis. Vaccination is a promising strategy to address this challenge. This study explores an innovative oral vaccination approach using a biomaterial-based scaffold encapsulated with an α-Ketoglutarate (AKG) adjuvant to combat E. tarda in Nile tilapia (Oreochromis niloticus). The scaffold was prepared through ion-gelation using chitosan and alginate, and its structural properties were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM). The vaccinated group exhibited significantly higher levels of lysozyme, myeloperoxidase, antiprotease, and superoxide dismutase compared to the control group (P < 0.05). Furthermore, increased levels of specific antibody Immunoglobulin M (IgM) were observed, with notable differences between the prime and booster vaccinations. The treatment group fed with the AKG-encapsulated vaccine demonstrated high survival rates. Histological analyses of the spleen, kidney, brain, and gut at 45 days post-vaccination (dpv) confirmed the vaccine's efficacy. These findings highlight the potential of this scaffold-based oral vaccine delivery system as a novel and effective approach for aquaculture. This strategy could also be adapted for the delivery of other vaccines and therapeutics in aquatic species.