Development of a test to identify pathogens (bacteria and virus) that cause diseases in fish from fish farms through environmental DNA (eDNA)

• Grant number: 23/12685-0
• Support Opportunities: Research Grants - Innovative Research in Small Business - PIPE
• Duration: March 01, 2024 - February 28, 2026
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Tiago Milanin
• Grantee: Tiago Milanin
• Host Company: Tiago Milanin
• CNAE: Aqüicultura em água doce
• City: Pirassununga
• Associated researchers: Antonio Augusto Mendes Maia ; Heidge Fukumasu ; Ricardo Luiz Moro de Sousa
• Associated scholarship(s): 24/01306-0 - Development of a test to identify pathogens (bacteria and viruses) that cause diseases in farmed fish based on environmental DNA (eDNA), BP.TT; 24/01323-2 - Development of a test to identify pathogens (bacteria and virus) that cause diseases in fish from fish farms through environmental DNA (eDNA), BP.PIPE

Abstract

The cultivation of aquatic organisms is the agricultural sector that has grown the most in recent years, with Brazil being one of the world's main producers of freshwater fish. Along with this productive increase, there is also an increase in the frequency and intensity of disease outbreaks, leading to serious economic losses. In an attempt to reduce such losses, management within the fish farm is often done inappropriately. In this context, in many cases, the fish farmer is unaware of the etiologic agent of the disease, which may result in the inappropriate use of massive amounts of chemical products in fish farms, resulting in burdensome processes and the emergence of resistant strains, a strong threat to fish farming and health public. The traditional diagnosis of diseases caused by bacteria and viruses in fish is time-consuming, since it depends on labor to collect sick specimens and send these fish to diagnostic laboratories. The tests still depend on the euthanasia of the fish, exposure of the organs and cultivation of bacteria to identify which species is related to the pathology and death of the fish. These methods of identifying pathogens take time, and the lack of an early diagnosis can compromise the entire breeding system, which can cause serious economic losses. Therefore, it is essential to develop a diagnostic test to identify the main species of bacteria (and virulence genes) and viruses related to fish diseases. In this way, the fish farmer will be able to anticipate the problem by taking prophylactic measures, ensuring that their tanks are suitable for raising fish and demanding that the specimens purchased also have the certification of origin from an environment free of contamination by pathogens. The objective of the project in phase 1 was to develop a diagnostic test to identify the main species of bacteria (Aeromonas hydrophila, Francisella noatunensis subsp. Orientalis, Streptocoocus agalactiae and virulence genes) that infect farmed fish through environmental DNA (eDNA) and a multiplex reaction of quantitative PCR (qPCR), and that was consistent with the need of the Brazilian market. A very important step during phase 1 was to optimize a water sampling protocol that would allow bacteria to be retained on membranes for later DNA extraction and PCR evaluation. For Phase 2, we expect to increase our testing portfolio and include the following pathogens in our diagnostics: Lactococcus petauri, Salmonella enterica (and virulence genes) and Splenic and Renal Infectious Necrosis Virus (ISKNV) from eDNA. (AU)