Innate immunity of Nile tilapia (Oreochromis niloticus) and the interaction between virus and bacteria: an in vitro co-infeccion model of macrophages by Ranavirus and Aeromonas hydrophila

• Grant number: 23/00903-2
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: May 01, 2024
• End date: April 30, 2026
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
• Principal Investigator: Ricardo Luiz Moro de Sousa
• Grantee: Nycolas Levy Pereira
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated research grant: 21/11955-8 - Solutions for emerging diseases in fish farming: diagnosis, vaccines and breeding, AP.CCD

Abstract

The fast growth of the world and Brazilian aquaculture have resulted in the increase in number and intensity of diseases outbreaks. Such outbreaks become a greater problem due to the higher number of pathogenic organisms present in the aquatic environment and the possible interaction of such organisms in the same host. Although the vast literature regarding diseases of aquatic organisms, concomitant infections in the same hosts caused by genetically different pathogens, as known as coinfections, are poorly investigated in fish, being commonly separated in primary and opportunistic infections. In the past few years, the interest about coinfections have increased, mainly because the harm presented by the synergy between such organisms, that leads to higher disease severity, and results in even higher mortality and economic losses. Among the pathogenic combinations of greater synergic potential, and consequently, more harmful to the host and to aquaculture, it is the combination virus-bacteria. The synergy between them occurs due to the immunosuppressing effects that some viruses impose to the host, in the cell level or systemically. The Frog Virus 3 (FV3) is a virus with immunosuppressing potential and one of the causative agents of ranavirosis, a disease considered emergent and already detected by our group in amphibious and in a Neotropical fish species. Moreover, FV3 is known for using the macrophages, one of the most important defense cells for teleost, as a reservoir and for viral proliferation. FV3 uses the macrophage machinery for viral metabolic activities, mainly, when the macrophages are activated by a secondary pathogen. Thus, the objectives of this project are better to understand the interactions virus-host in O. niloticusm through in vitro techniques; to investigate the immunosuppressing effects of ranavirosis in macrophages of a tropical aquaculture model, as well as the methods of immunological evasion and utilization of cell machinery; and to evaluate the harm of FV3 infection for the macrophage genotypical and phenotypical responses in front of a bacterial infection.