Bivalent Vaccine against Streptococcus agalactiae and Aeromonas hydrophila in Nile Tilapia (Oreochromis niloticus): A Laboratory-Phase and Large-Scale Study
Açucena Veleh Rivas, Angelo Gabriel Vidal dos Santos, Adrieli Barboza de Souza, Gilson Bueno Junior, Gabriela Fernandes de Souza, Estevam Martins de Souza, Louisiane de Carvalho Nunes, Kelvinson Fernandes Viana
Abstract
One of the main factors limiting tilapia’s production is the occurrence of infections caused by Aeromonas and Streptococcus species. This work intended to evaluate a bivalent vaccine against A. hydrophila and S. agalactiae by intraperitoneal (i.p) administration in Nile tilapia (Oreochromis niloticus) in Brazil. The study was carried out in two phases: one in the laboratory, on a small scale, and from the results obtained, the study was expanded to a large scale in a production system in cages. The vaccine proved to be safe and effective in laboratory tests, with a vaccine efficacy (VE) of 93.66%. However, in large-scale tests with 12,000 tilapias, the VE was 59.14%, with a better food conversion ratio (1.54 kg) in the vaccinated group compared to the control group (1.27 kg). These results corroborate the efficiency of this tested vaccine; however, they indicate the need for field tests to attest to real protection.