Immune responses induced by inactivated vaccine against Aeromonas hydrophila in pacu, Piaractus mesopotamicus

Made available in DSpace on 2020-12-12T02:01:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Aeromonas hydrophila is responsible for outbreaks of a severe infectious disease in fish farms around the world and is one of the major causes of economic losses to the neotropical fish farmers. This study assessed the induction of immune responses and protection against A. hydrophila in pacu, Piaractus mesopotamicus, vaccinated through intraperitoneal and immersion route with inactivated virulent strain. Fish were randomly distributed in three vaccinated groups: intraperitoneal (i.p.) route; immersion; and immersion + booster; and control group (unvaccinated). All vaccination protocols used the concentration of 1.7 × 108 CFU mL−1 of inactivated A. hydrophila., and an oil adjuvant was used for vaccine prepararion for i.p. route vaccination. Blood and skin mucus from 9 fishes per treatment were collected at 14, 28, 42 and 84 days post-vaccination (DPV) for determination of lysozyme concentration in skin mucus, as well as antibodies anti-A. hydrophila in blood serum and skin mucus. Fish were challenged at 84 DPV with homologous and virulent strain of A. hydrophila for evaluation of resistance against bacterial infection. The results demonstrated that vaccination with inactivated A. hydrophila suspension by i.p. or immersion resulted in significant increase of skin mucus lysozyme and specific antibody levels in serum and skin mucus, at 28 and 42 DPV, and this increase in innate and adaptive immunity remained significant in pacu vaccinated through i.p. route up to 84 DPV. Although no significant differences were observed in the survival study, pacu vaccinated through i.p. route presented 31,33% of relative percentage survival (RPS) in LD50–96h when compared unvaccinated fish challenged at 84 DPV. The results observed in this study indicate that vaccination programs with inactivated A. hydrophila, including booster doses by i.p. or immersion routes, could result in more effective protection in pacu against this bacteriosis, by increasing innate and adaptive mucosal and systemic immune responses. Laboratory of Aquatic Organisms Pathology (Lapoa) Aquaculture Center from UNESP (CAUNESP), Rodovia de Acesso Paulo Donato Castellane s/n Department of Microbiology Faculty of Sciences University of Malaga Department of Preventive Veterinary Medicine São Paulo State University (Unesp), Rodovia de Acesso Paulo Donato Castellane s/n, Zona Rural Department of Microbiology São Paulo State University (Unesp), Rodovia de Acesso Paulo Donato Castellane s/n, Zona Rural Laboratory of Animal Pharmacology and Toxicology Brazil University, Av. Hilário da Silva Passos, 950 Laboratory of Aquatic Organisms Pathology (Lapoa) Aquaculture Center from UNESP (CAUNESP), Rodovia de Acesso Paulo Donato Castellane s/n Department of Preventive Veterinary Medicine São Paulo State University (Unesp), Rodovia de Acesso Paulo Donato Castellane s/n, Zona Rural Department of Microbiology São Paulo State University (Unesp), Rodovia de Acesso Paulo Donato Castellane s/n, Zona Rural FAPESP: 2012/12256-7 CNPq: 432830/2016-2