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Mechanisms of natural resistance of Nile Tilapia to Streptococcus agalactiae infection

Grant number: 16/18345-2
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): March 01, 2017
Effective date (End): February 28, 2019
Field of knowledge:Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
Principal Investigator:Julieta Rodini Engracia de Moraes
Grantee:Jefferson Yunis Aguinaga
Home Institution: Centro de Aquicultura (CAUNESP). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil


Nile tilapia present great genetic diversity due to abundant and multiple spawns increasing the possibility that a group of these individuals have a particular genetic combination that confers resistance to bacteria. Understanding the mechanisms involved in this process means a breakthrough and challenge in the fight against these diseases. The aim of this study will be to elucidate the mechanisms of action of Nile tilapia naturally resistant to Streptococcus agalactiae. For this, it will be used 408 Nile tilapia (about 200g weight) from a Nile tilapia family where there were found resistant individuals to this bacterium. Fish will be identified with microchips and distributed in water tanks of 300 L with continuous flow of water at a density of 25 fish per box. 48 fish will be used to perform the LD 50-10 days. Screening will be held with 30 animals to discard previous infection by S. agalactiae. Another 30 fish will be injected with sterile saline (control group). The remaining animals will be inoculated with S. agalactiae. Animals will be inoculated with LD 50 of S. agalactiae. Then, it will performed the collection of blood after 5 days of inoculation, whereas in this time it is possible to differentiate the animals susceptible from resistant by clinical signs. The following analyzes will be performed: clinical examination, hematology, serum biochemistry variables, cortisolemia, glycemia, respiratory burst of blood leukocytes, lysozyme activity, serum lytic activity, bacterial agglutination, hemolytic complement activity, survival percentage and analysis of the transcriptome of blood leukocytes. For the latter will only be used 100 fish between resistant and susceptible. Fish will be accompanied by up to three weeks after collection to assess the survival and check the resistance or susceptibility. Finally, for statistical analysis will be considered the control group, susceptible and resistant animals considering survival at 3 weeks. (AU)

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
RAMOS-ESPINOZA, FERNANDO CARLOS; CUEVA-QUIROZ, VICTOR ALEXANDER; YUNIS-AGUINAGA, JEFFERSON; ENGRACIA DE MORAES, JULIETA RODINI. A comparison of novel inactivation methods for production of a vaccine against Streptococcus agalactiae in Nile tilapia Oreochromis niloticus. Aquaculture, v. 528, NOV 15 2020. Web of Science Citations: 0.
CUEVA-QUIROZ, VICTOR ALEXANDER; YUNIS-AGUINAGA, JEFFERSON; RAMOS-ESPINOZA, FERNANDO CARLOS; DE MORAES, FLAVIO RUAS; ENGRACIA DE MORAES, JULIETA RODINI. Acute hypercortisolemia inhibits innate immune parameters in Piaractus mesopotamicus experimentally infected with Aeromonas hydrophila. Aquaculture, v. 523, JUN 30 2020. Web of Science Citations: 0.
ALVAREZ-RUBIO, NORQUIS CALED; YUNIS-AGUINAGA, JEFFERSON; CALA-DELGADO, DANIEL L.; CUEVA QUIROZ, VICTOR ALEXANDER; MIANI VERRI, BRUNO LUIS; RAMOS ESPINOZA, FERNANDO CARLOS; ENGRACIA DE MORAES, JULIETA RODINI. Influence of hand net mesh type and sex on experimental infection with Aeromonas hydrophila in Brazilian native fish Astyanax altiparanae. AQUACULTURE REPORTS, v. 16, MAR 2020. Web of Science Citations: 0.

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