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Cycle 5 (2015 Deadline)

Enhanced research capacity and fish health infrastructure to assist Tunisian aquaculture

PI: Nadia Chérif (, Institut National des Sciences et Technologies de la Mer (INSTM)
U.S. Partner: James Winton, U.S. Geological Survey, Western Fisheries Research Center

Project Overview:

Aquaculture is the fastest growing food-production sector in the world, providing a significant supplement to aquatic organisms harvested from the wild. However, the high density of animals reared in intensive aquaculture frequently produces infectious diseases that have emerged as major constraints to the successful development of aquaculture in many areas of the world. The project will support both basic and applied research that will generate tools and knowledge needed for promoting social acceptance and good governance of Tunisian aquaculture, as well as solutions for sustainable production. The project has three objectives: (1) establishment of a Phase-1 prototype aquatic health network, an initiative towards development of a National Aquatic Health Network (NAHN) for Tunisia; (2) development of improved surveillance tools and characterize host defense mechanisms; (3) application of nodavirus RNA3 as a biosensor. Key benefits from the research include providing an enabling environment for sustainable aquaculture, protecting investments from aquatic diseases and pests, and increasing research capacity for the prevention, early detection, and response to aquatic disease threats.

This project combines expertise in genomics, fish virology, biotechnology, and immunology to enhance technical capacities for improving aquaculture productivity and marketing in Tunisia. It also represents an exciting opportunity to use novel molecular approaches including biosensor technology to answer questions about the viral status of commercially important aquaculture species, potentially serving as an early warning system to prevent diseases that could affect fish harvests. Planned capacity building activities under the project include proficiency testing and assay validation with the aid of the laboratory of the U.S. partner. Other components of the training will include proper sampling protocols for fish, as well as recruitment and training of lab technicians across Tunisia. Another important product of this initiative will be the assessment of to a national fish health program. Other products include the results from research on the effects of immune stimulants on the health of fish in aquaculture farms in Tunisia and an expanded understanding of their impact on antiviral immunity. The results will be shared with stakeholders and will be used at the end of the validation stage.

Summary of Recent Activities: 

As of November 2017, the project organized into three work packages (WP). These include WP1: Establishment of a Phase-1 prototype aquatic health network: an initiative towards development of a National Aquatic Health Network (NAHN) for Tunisia; WP2: Development of improved biotechnological tools for the detection of aquatic viruses; and WP3: Assessment of RNA transcription after treatment with probiotic bacteria and active biomolecules.

In order to achieve better management of the fish health sector in Tunisia during the period of the project, the aim of work package 1 (WP1) was mainly to transition from a passive surveillance system applied during several year for the zoo sanitary survey of fish farms, to an active and targeted surveillance approach. Tunisian farmed sea bass and sea bream will be the target fish species and a focus on two diseases (VHSV and IHNV).

The second work package (WP2) of CapTunHealth concerns the development of improved biotechnological tools for the detection of aquatic viruses. The first innovative goal was the development of new biosensors specific for the detection of the Nodavirus RNA genome within sick fish or healthy carriers of the virus. The Nodavirus causes severe mortalities and economical loss once introduced in a fish farm. No vaccines are available in order to prevent the disease; hence, prophylactic measures and early diagnosis are the only mean to avoid disasters caused by the virus. The project acquired specific electrodes necessary for the detection system using nanotechnology. Advanced genomic tools assist in determining the best sequence of the genomic viral nucleic acid to target. This choice will permit the detection of all types published of Nodaviurs. Furthermore, a second new tool for diagnostic will be developed by screen an available dromedary VHH library against the fish-infective nodavirus (betanodavirus), causing acute disorders and lethal neurological necrosis in fish, with the main objective to select new nodavirus antibody "binders".

The third work package (WP3) describes our research approach related to the evaluation of some bioactive molecules to be used as probiotic boosting the fish immune system or as inhibitors of aquatic pathogens. The chitosan extracted from shellfish was tested to inhibit the expression of Nodaviurs in-vitro using fish cell lines and the team obtained promising results. The research team quantified a panel of innate immune genes using molecular techniques after cells treatment with Chitsan. One of the genes showed a significant transcription increase. They also evaluated Lactic bacteria E. facium for potential inhibiting effect on nodavirus in-vitro. The team was able to verify their hypothesis after treating the cells with a solution including the bacteria. Results were reproducible and are ready to be tested in-vivo.

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