This study evaluated the effects of dietary supplementation with 0.3% Saccharomyces cerevisiae yeast cell wall and of vaccination against Streptococcus agalactiae on the cellular component of acute inflammation induced in the coelomic cavity of Nile tilapia Oreochromis niloticus and on survival of the fish after challenge. A total of 84 tilapia of mean (± SD) weight 125.0 ± 1.5 g were distributed among twelve 310 l fiberglass tanks according to a 2 × 2 × 3 factorial design in the following manner: with and without supplementation; 2 stimulations (oily solution without S. agalactiae vaccine and vaccination); 15 d later all fish were intracoelomically challenged with 10 8 CFU ml -1 of a homologous strain of S. agalactiae, and evaluated after 6, 24 and 48 h, with 7 replicates. The fish received the non-supplemented or supplemented diet for a total of 77 d. The vaccination was performed on the 60th day, intracoelomically, as a single injection of 0.5 ml of the vaccine containing 10 8 CFU ml −1. Fifteen days later, all the fish were challenged with S. agalactiae by means of an intracoelomic inoculation of 10 8 CFU ml −1. No mortality was observed among the supplemented fish. The fish that were fed the non-supplemented diet and immunized with the bacterium presented a mortality rate of 28.5%. Among the non-supplemented and nonimmunized fish, the mortality rate was 38.09%. Supplementation, in both vaccinated and nonvaccinated fish, induced larger accumulations of thrombocytes, lymphocytes and macrophages at the inflammatory focus. The results suggest that supplementation with 0.3% yeast cell wall, in both vaccinated and non-vaccinated fish, improved the in flammatory response of the fish and protected against the challenge. Vaccination increased the defense response, but the effect was stronger when associated with supplementation with S. cerevisiae. KEY WORDS: Inflammation · Saccharomyces cerevisiae · Vaccination · Streptococcus agalactiae · ChallengeResale or republication not permitted without written consent of the publisher

Resumo -O objetivo deste trabalho foi avaliar a inter-relação entre a suplementação alimentar com parede celular de Saccharomyces cerevisae e a vacinação contra Streptococcus agalactiae e seu efeito sobre o desempenho produtivo e as variáveis hematológicas de tilápia-do-nilo (Oreochromis niloticus). Oitenta e quatro tilápias-do-nilo foram distribuídas em 12 caixas de fibra (n=7), em arranjo fatorial 2x2x3, correspondente a dois níveis de suplementação com parede celular de levedura, dois tipos de inoculação e três tempos de avaliação. Os peixes foram alimentados durante 77 dias. A vacinação dos peixes foi realizada 60 dias após o início da alimentação. Quinze dias após a vacinação, todos os peixes foram submetidos ao desafio com cepa viva de S. agalactiae, e 6, 24 e 48 horas após o desafio, o sangue foi colhido da veia caudal para avaliações. Peixes alimentados com ração suplementada apresentam maior ganho de peso e taxa de crescimento específico, e a interação entre os efeitos da dieta e da vacinação resulta em maiores taxas de hematócrito, hemoglobina e leucócitos.Termos para indexação: Oreochromis niloticus, inflamação, probiótico, sangue, teleósteos, vacinação. Performance and hematological profile of Nile tilapia fed with Saccharomyces cerevisiae and vaccinated against Streptococcus agalactiaeAbstract -The objective of this work was to evaluate the inter-relationship between dietary supplementation with Saccharomyces cerevisiae cell wall and vaccination against Streptococcus agalactiae, and its effect on the productive performance and hematological variables of Nile tilapia (Oreochromis niloticus). Eighty-four Nile tilapia were distributed in 12 fiber boxes (n=7), in a 2x2x3 factorial arrangement, corresponding to two levels of supplementation with yeast cell wall, two types of inoculation, and three evaluation times. Fish were fed during 77 days. Vaccination of fish was done 60 days after feeding started. Fifteen days after vaccination, all fish were subjected to challenge with live strain of S. agalactiae, and 6, 24, and 48 hours after the challenge, blood was collected from the caudal vein for evaluations. Fish fed with supplemented diets show greater weight gain and specific growth rate, and the interaction between the diet and vaccination effects results in higher hematocrit, hemoglobin, and leukocyte rates.

Streptococcosis is one of the most important diseases in aquaculture, causing high rates of mortality in fish. ArtinM, an immunostimulant obtained from jackfruit (Artocarpus integrifolia) seed extract, enhances the innate immune response. The aim of this study was to examine the action of ArtinM on neutrophil haptotaxis to the peritoneal cavity of juvenile Nile tilapia (Oreochromis niloticus) inoculated intraperitoneally with Streptococcus agalactiae. After establishing the LD50 of S. agalactiae and the effective dose of ArtinM, 120 animals randomly distributed in 12 aquaria were divided into the following four treatment groups: G1, control; G2, via the intraperitoneal (i.p.) route inoculation with ArtinM; G3, i.p. inoculation with S. agalactiae and G4, i.p. inoculation with ArtinM and challenge with S. agalactiae. Six and 24 hours after treatment, the fish were sacrificed and peritoneal exudate and caudal vein blood samples were collected for analysis of the total number of leukocytes and neutrophils. To establish the optimal ArtinM concentration, the results were analyzed with a chi-square test at a 1% significance level. The experimental inoculation and challenge results were analyzed with the SASM-Agri software developed by Canteri et al. (2001) using the Scott-Knott's test at a 5% significance level. The results of this study showed that i.p. inoculation with 1.0 µg ArtinM/animal has an effect on neutrophil haptotaxis to the peritoneal cavity in juvenile Nile tilapia. Therefore, ArtinM might represent a suitable prophylactic alternative in juvenile Nile tilapias inoculated with S. agalactiae.