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Aquaculture of European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) is an essential activity in the Mediterranean basin. Several EU Horizon 2020 and regional projects are focusing on the improvement of their farming performance. This workshop aimed at displaying, sharing and discussing projects’ achievements among interested colleagues engaged to work with fish diseases. The most innovative research outputs aiming to improve the European mariculture were presented during this workshop, including updates from EU Horizon 2020 projects MedAID, PerformFISH, ParaFishControl, FutureEUAqua and the Italy-Croatia Interreg project AdriAquaNet.

Aquaculture of European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) is an essential activity in the Mediterranean basin. Several EU Horizon 2020 and regional projects are focusing on the improvement of their farming performance. This workshop aimed at displaying, sharing and discussing projects’ achievements among interested colleagues engaged to work with fish diseases. The most innovative research outputs aiming to improve the European mariculture were presented during this workshop, including updates from EU Horizon 2020 projects MedAID, PerformFISH, ParaFishControl, FutureEUAqua and the Italy-Croatia Interreg project AdriAquaNet

Maybe most characteristic of the TargetFish project, which kicked off some five years ago with 30 partners from 10 EU member states, two associated countries (Norway, Israel) and one international cooperation partner country (Chile), has been the close cooperation between research groups and enterprises; more or less equally represented in this large consortium. In this respect, TargetFish has been revolutionary validating by this close cooperation fundamental knowledge for the development of next generation vaccines and different routes of vaccine administration. TargetFish had the ambition to demonstrate market applicability of improved vaccines or new prototype vaccines that would come forward from the project. Via frequent joint meetings of its partners, be it research group or enterprise, TargetFish aimed to drive vaccine development in an industrial applicable way. This could facilitate adoption of new intellectual property and stimulate the presentation of new fish vaccines on the market. The industry forum has been a platform for a continuing validation of the applied potential of the research outcomes. Workshops were organised at the different EAFP meetings to communicate the validation process to those not directly involved with the project but interested in the fish vaccine market. After a kick-off meeting during the EAFP in Tampere, Finland fours years ago and a second meeting at the EAFP in Las Palmas, Spain, two years ago, at the present EAFP in Belfast, Northern Ireland a final meeting was organised. This report is a summary of the 'Industrial Forum workshop' held at the EAFP in Belfast 2017 and provides a short overview of the highlights presented to, and discussed with, those present and interested in DNA vaccine development, policies and laws, production and delivery routes.

Maybe most characteristic of the TargetFish1 project, which kicked off some five years ago with 30 partners from 10 EU member states, two associated countries (Norway, Israel) and one international cooperation partner country (Chile), has been the close cooperation between research groups and enterprises; more or less equally represented in this large consortium. In this respect, TargetFish has been revolutionary validating by this close cooperation fundamental knowledge for the development of next generation vaccines and different routes of vaccine administration. TargetFish had the ambition to demonstrate market applicability of improved vaccines or new prototype vaccines that would come forward from the project. Via frequent joint meetings of its partners, be it research group or enterprise, TargetFish aimed to drive vaccine development in an industrial applicable way. This could facilitate adoption of new intellectual property and stimulate the presentation of new fish vaccines on the market. The industry forum has been a platform for a continuing validation of the applied potential of the research outcomes. Workshops were organised at the different EAFP meetings to communicate the validation process to those not directly involved with the project but interested in the fish vaccine market. After a kick-off meeting during the EAFP in Tampere, Finland fours years ago and a second meeting at the EAFP in Las Palmas, Spain, two years ago, at the present EAFP in Belfast, Northern Ireland a final meeting was organised. This report is a summary of the 'Industrial Forum workshop' held at the EAFP in Belfast 2017 and provides a short overview of the highlights presented to, and discussed with, those present and interested in DNA vaccine development, policies and laws, production and delivery routes.

Although spring viremia of carp virus (SVCV) can cause high mortalities in common carp, a commercial vaccine is not available for worldwide use. Here, we report a DNA vaccine based on the expression of the SVCV glycoprotein (G) which, when injected in the muscle even at a single low dose of 0.1 µg DNA/g of fish, confers up to 100% protection against a subsequent bath challenge with SVCV. Importantly, to best validate vaccine efficacy, we also optimized a reliable bath challenge model closely mimicking a natural infection, based on a prolonged exposure of carp to SVCV at 15°C. Using this optimized bath challenge, we showed a strong age-dependent susceptibility of carp to SVCV, with high susceptibility at young age (3 months) and a full resistance at 9 months. We visualized local expression of the G protein and associated early inflammatory response by immunohistochemistry and described changes in the gene expression of pro-inflammatory cytokines, chemokines, and antiviral genes in the muscle of vaccinated fish. Adaptive immune responses were investigated by analyzing neutralizing titers against SVCV in the serum of vaccinated fish and thein vitroproliferation capacity of peripheral SVCV-specific T cells. We show significantly higher serum neutralizing titers and the presence of SVCV-specific T cells in the blood of vaccinated fish, which proliferated upon stimulation with SVCV. Altogether, this is the first study reporting on a protective DNA vaccine against SVCV in carp and the first to provide a detailed characterization of local innate as well as systemic adaptive immune responses elicited upon DNA vaccination that suggest a role not only of B cells but also of T cells in the protection conferred by the SVCV-G DNA vaccine.

International audience

Surveys among wild marine fish have revealed occurrence of viral haemorrhagic septicaemia virus (VHSV) infections in a high number of diverse fish species. In marine aquaculture of rainbow trout, preying on invading wild fish might thus be a risk factor for introduction and adaptation of VHSV and subsequent disease outbreaks. Our objective was to determine whether an oral transmission route for VHSV in rainbow trout exists. Juvenile trout were infected through oral, waterborne and cohabitation transmission routes, using a recombinant virus strain harbouring Renilla luciferase as reporter gene. Viral replication in stomach and kidney tissue was detected through bioluminescence activity of luciferase and qRT-PCR. Replication was detected in both tissues, irrespective of transmission route. Replication patterns, however, differed among transmission routes. In trout infected through oral transmission, replication was detected in the stomach prior to kidney tissue. In trout infected through waterborne or cohabitation transmission, replication was detected in kidney prior to stomach or in both tissues simultaneously. We demonstrate the existence of an oral transmission route for VHSV in rainbow trout. This implies that preying on invading infected wild fish is a risk factor for introduction of VHSV into marine cultures of rainbow trout.

International audience