Dysregulation of B Cell Activity During Proliferative Kidney Disease in Rainbow Trout. Frontiers in Immunology. doi.org/10.3389/fimmu.2018.01203

Proliferative kidney disease (PKD) is a widespread disease caused by the endoparasite Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea). Clinical disease, provoked by the proliferation of extrasporogonic parasite stages, is characterized by a chronic kidney pathology with underlying transcriptional changes indicative of altered B cell responses and dysregulated T-helper cell-like activities. Despite the relevance of PKD to European and North American salmonid aquaculture, no studies, to date, have focused on further characterizing the B cell response during the course of this disease. Thus, in this work, we have studied the behavior of diverse B cell populations in rainbow trout (Oncorhynchus mykiss) naturally infected with T. bryosalmonae at different stages of preclinical and clinical disease. Our results show a clear upregulation of all trout immunoglobulins (Igs) (IgM, IgD, and IgT) demonstrated by immunohistochemistry and Western blot analysis, suggesting the alteration of diverse B cell populations that coexist in the infected kidney. Substantial changes in IgM, IgD, and IgT repertoires were also identified throughout the course of the disease further pointing to the involvement of the three Igs in PKD through what appear to be independently regulated mechanisms. Thus, our results provide strong evidence of the involvement of IgD in the humoral response to a specific pathogen for the first time in teleosts. Nevertheless, it was IgT, a fish-specific Ig isotype thought to be specialized in mucosal immunity, which seemed to play a prevailing role in the kidney response to T. bryosalmonae. We found that IgT was the main Ig coating extrasporogonic parasite stages, IgT+ B cells were the main B cell subset that proliferated in the kidney with increasing kidney pathology, and IgT was the Ig for which more significant changes in repertoire were detected. Hence, although our results demonstrate a profound dysregulation of different B cell subsets during PKD, they point to a major involvement of IgT in the immune response to the parasite. These results provide further insights into the pathology of PKD that may facilitate the future development of control strategies.

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Press Release: June 2018

A recent study conducted by the EU Horizon 2020-funded ParaFishControl project aimed to demonstrate the absence of zoonotic parasitic worms in European farmed fish, specifically in gilthead sea bream, European sea bass, turbot, Atlantic salmon, rainbow trout and common carp. Zoonotic parasites are transmitted from animals to humans; zoonotic worms (helminths) can spread to humans when infected fish is consumed raw or partially cooked. From spring 2016 to winter 2017, more than 7,000 fish were analysed from commercial aquaculture farms throughout Europe, including Croatia, Denmark, Greece, Hungary, Italy, Norway, Spain, and Turkey. No zoonotic parasitic helminths, such as Anisakis, were found in any of the examined fish, at a confidence level of 95-99%.

This is the largest study ever conducted in Europe and the results have been even better than expected. “This is great news for European aquaculture” said Dr Miguel Ángel Pardo from AZTI Tecnalia, ParaFishControl project partner, “results indicate that consuming fish from European farms presents negligible risk for human health when it comes to zoonotic parasitic worms.”

These results are part of a larger survey of marine and freshwater farmed fish undertaken by ParaFishControl, which aims to improve our understanding of fish-parasite interactions and develop innovative solutions and tools to prevent, control and mitigate harmful parasites which affect the main fish species farmed in Europe. This effort was part of the “Fish Product Safety” work package, led by AZTI in collaboration with six other consortium members from across Europe (Spanish National Research Council, University of Bologna, Hungarian Academy of Sciences, University of Copenhagen, Hellenic Centre for Marine Research, and University of Bergen).

Dr Miguel Ángel Pardo explained the importance of these positive results, which “have led us to design more specific research to be carried out on runts as a potential parasite carrier and the feed as possible transmission vector. This will allow us to assess all the crucial aspects in the infection of fish by zoonotic parasites”.

The study itself will be published in peer-review journals and will be accessible through the ParaFishControl project website. These results are a significant indicator of the overall success of the project thus far, with the overlying goal of safe and sustainable European seafood clearly being met. The final outputs of ParaFishControl will allow European farmers to manage their risk at very low levels, which will differentiate high quality European aquaculture products from others worldwide.

For more information on the project, please watch the ParaFishControl video: www.youtube.com/watch?v=9gjvZVUxh_Y

For more information and press queries, contact Marieke Reuver, AquaTT Programme Manager, email: marieke@aquatt.ie

Fish being prepared to be sold in a fish market (unsplash).

Press Release: September 2017

Aquaculture industry and research representatives participated in the first ParaFishControl Industry Forum on Tuesday 5 September in Belfast, Northern Ireland. The event was part of the 18th International Conference on Diseases of Fish and Shellfish, and aimed to explore how the European aquaculture sector could benefit from the latest research in the area. The event facilitated effective knowledge exchange on the latest developments in fighting parasitic disease affecting aquaculture, between academia, industrial companies and fish farmer associations. This is an important goal of the ParaFishControl project, an EU Horizon 2020-funded research project that aims to improve our understanding of fish-parasite interactions and develop innovative solutions and tools to prevent, control and mitigate harmful parasites which affect the main fish species farmed in Europe.

ParaFishControl Industry Forum leader Dr Panos Christofilogiannis from AQUARK remarked “We are excited to discuss ways to improve parasitic disease management and to quantify its economic impact to the sector. This serves as the first step to mobilise all stakeholders in a sector-wide effort to combat and manage fish parasitic diseases with novel approaches and solutions. We are confident that the ParaFishControl project knowledge outputs will contribute greatly, and the Industry Forum is the right platform to do so.” 

Dr Hamish Rodger, Global Managing Director of the FishVet Group, estimated the high annual economic impact for a variety of parasitic diseases in different countries, like sea lice in Norway (448-640 million Euros) and Scotland (40-56 million Euros), amoebic gill disease in Scottish farms (600-900K Euros for a 2000 tonne site) and cotton moulds (Saprolegnia) in Scottish aquaculture (5.5 million Euros).  Mr Niels Henriksen, Danish Aquaculture Association fish pathologist, provided insights on carp and trout aquaculture, and estimated the annual impact of parasitic diseases on European trout farming to be between 30 and 60 million Euros. The impact of parasitic diseases in Mediterranean mariculture was discussed by Mr Andreas Kyriakou, fish pathologist at SELONDA Group. All attendees agreed that a coordinated effort is required involving open communication between fish pathologists, fish farmer associations and scientists, to improve impact predictions and the use of a harmonised methodology to accurately assess the significant economic impact of parasites in aquaculture.

In the second session of the ParaFishControl Industry Forum, the latest research findings and future solutions resulting from the ParaFishControl project were presented and discussed, with a focus on their relevance to the aquaculture industry and the strategy to effectively transfer these results to applied solutions for the sector. Particularly exciting news included novel disease treatments which are planned to be ready for use in the near future, progress in the ongoing search for vaccination candidate genes and feed additives, and the expectations of further expert consultations and epidemiological investigations to be undertaken in 2018.

ParaFishControl Project Coordinator Dr Ariadna Sitjà-Bobadilla, of Consejo Superior de Investigaciones Científicas (CSIC), recognised the value of events such as the ParaFishControl Industry Forum, “which brings stakeholders from both science and industry together, highlighting the role of partnerships and collaborative approaches to instigate real and profound change. It is really exciting to witness evidence based science being recognised as being applicable by industry and subsequently being used in a real world setting with affirmative and measurable results”.

The open discussion was launched with a short presentation by Mr Andrea Fabris, FEAP Fish Health Committee, fish pathologist API, who highlighted the industry priorities on the management and impact of parasitic diseases and the interest for an effective transfer of the project results to industry, leading to concrete suggestions for future ParaFishControl activities. This discussion proved to be a thought-provoking session to round off what was a very exciting event!

To find out more about the recent research findings from ParaFishControl, please visit the project’s website: www.parafishcontrol.eu

Industry stakeholders and interested parties are invited to join the ParaFishControl LinkedIn group to follow the projects’ progress: www.linkedin.com/groups/8429051/profile

ParaFishControl partners and industry experts attending the ParaFishControl Industry Forum at the 18^th International Conference on Diseases of Fish and Shellfish, front row, from left: Dr Birgit Oidtmann (Cefas, UK), Dr Ariadna Sitjà-Bobadilla (CSIC, ES), Prof James Bron (UoS, UK), Mr Niels Henriksen, DAA, DK); top row, from left: Dr Panos Christofilogiannis (AQUARK, GR), Mr Andreas Kyriakou (SELONDA, GR), Dr Hamish Rodger (FishVet, IE), Dr Simon Jones (DFO, CA), Dr Oswaldo Palenzuela (CSIC, ES), Dr Niels Lorenzen (DTU, DK) ©AquaTT 

For further information on the ParaFishControl project, please contact:
ParaFishControl Coordination and Management: parafishcontrol.coordination@csic.es, enric.belles-boix@inra.fr
ParaFishcontrol Industry Forum: panos@aquark.gr
ParaFishControl Communication and Press: marieke@aquatt.ie

The 18th International Conference on Diseases of Fish and Shellfish is organised by The European Association of Fish Pathologists (EAFP) in Belfast, 4-8 September 2017. For further information, please visit: eafp2017.com/

ParaFishControl is hosting an Industry Forum on Tuesday, 5 September, from 2:00-3:15pm and 3:45-6:15pm. The half hour break in between sessions allows participants to mingle and look at posters. 

The Industry Forum facilitates the engagement between the ParaFishControl consortium and industrial companies and fish farmer associations to ensure essential Knowledge Exchange. It is led by Dr. Panos Christofilogiannis (AQUARK), with support from AquaTT.

To download the announcement flyer, click here.

Industry stakeholders can join the ParaFishControl LinkedIn Group to follow the progress of this work, www.linkedin.com/groups/8429051.

Published: 24.08.2017