Immunomodulatory effects of lipopolysaccharide and its evaluation as an alternative to microbiological challenge in tilapia, Oreochromis nilotica

• Grant number: 16/21443-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2017
• End date: December 31, 2018
• Field of knowledge: Agronomical Sciences - Animal Husbandry
• Principal Investigator: Jaqueline Dalbello Biller Takahashi
• Grantee: Thaís Daltoso da Silva
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil
• Associated scholarship(s): 17/22934-6 - Comparative stress and immune responses in rainbow trout (Oncurhynvhus mykiss), gilthead seabream (Sparus aurata) after applying two stressors,anoxia and vaccination, BE.EP.IC

Abstract

Aquaculture in Brazil has been growing since the 80s, however these production intensification led to the various diseases outbreaks. So, many studies has been performed to evaluate immunostimulants action to avoid those infection, and most of them assess the effect on the resistance to diseases through microbiological challenges, however recently lipopolysaccharide (LPS) has been used to immune responses induction. This proposal aims to determine the best LPS concentration for the use as a challenge compound agent for tilapia, compared to the live microorganism challenge. A total of 288 tilapia juveniles will be divided into 6 treatments: PBS phosphate buffer (control), 100, 250, 500 and 600 ¼g/FW LPS and Streptococcus agalatiae with 4 replicates each. A basal sampling will be performed after fish acclimatization. Seventy-two hours after the challenge, 3 fish from each replicate (12 fish / treatment) will be randomly sampled. It will be assessed the immune responses (lysozyme activity, hemolytic activity of the complement, determination of respiratory activity of leukocytes), the hematological responses (hematocrit, red blood cell numbers, hemoglobin, mean corpuscular volume, total and differential count of the defense cells) and biochemical responses (protein total, albumin, globulin and index A: G). The mortality will be evaluated and removed daily for 30 days to determine survival rate. The experiment will be conducted in a completely randomized design. The results obtained will be submitted to analysis of variance and the means compared by the Tukey test (5%). (AU)