ParaFishControl, in collaboration with TechFish and DAFINET, are organising the training course Control of Parasitic Diseases in Aquacultured Fish – Innate and Acquired Resistance. This event will be held in the University of Copenhagen (Denmark) on the 30th of April 2019.

The course will include lectures, demonstrations and discussions by experts within specific disciplines related to fish pathology, immunology, disease control and genetics. The course will focus on the following topics: description of diseases in selected fish production systems, application of genomic tools, sustainable control methods, vaccination, as well as selective breeding as a way to improve health and reduce use of drugs and chemotherapeutants.

The participants are also invited to submit their abstracts in related topics for a 10-minutes presentation during the event. The deadline for abstract submission is the 5th of April 2019. More information on how to submit an abstract can be downloaded here.

The registration to the training course and the attendance to the social dinner is free of charge, but participants are expected to pay for their own travel, subsistence and accommodation.

More information about the training course can be found here.
To register for the training course, click here.

Background: Monogenean flatworms are the main fish ectoparasites inflicting serious economic losses in aquaculture.The polyopisthocotylean Sparicotyle chrysophrii parasitizes the gills of gilthead sea bream (GSB,Sparus aurata) causing anaemia, lamellae fusion and sloughing of epithelial cells, with the consequent hypoxia, emaciation, lethargy andmortality. Currently no preventive or curative measures against this disease exist and therefore information on the host-parasite interaction is crucial to find mitigation solutions for sparicotylosis. The knowledge about gene regulation inmonogenean-host models mostly comes from freshwater monopysthocotyleans and almost nothing is known about polyopisthocotyleans. The current study aims to decipher the host response at local (gills) and systemic (spleen, liver) levels in farmed GSB with a mild natural S. chrysophrii infection by transcriptomic analysis.

Results: Using Illumina RNA sequencing and transcriptomic analysis, a total of 2581 differentially expressed transcripts were identified in infected fish when compared to uninfected controls. Gill tissues in contact with the parasite (P gills) displayed regulation of fewer genes (700) than gill portions not in contact with the parasite (NP gills) (1235), most likely due to a local silencing effect of the parasite. The systemic reaction in the spleen was much higher than that at the parasite attachment site (local) (1240), and higher than in liver (334). NP gills displayed a strong enrichment of genes mainly related to immune response and apoptosis. Processes such as apoptosis, inflammation and cell proliferation dominated gills, whereas inhibition of apoptosis, autophagy, platelet activation, signalling and aggregation, and inflammasome were observed in spleen. Proteasome markers were increased in all tissues, whereas hypoxia-related genes were down-regulated in gills and spleen.

Conclusions: Contrasting forces seem to be acting at local and systemic levels. The splenic down-regulation could be part of a hypometabolic response, to counteract the hypoxia induced by the parasite damage to the gills and to concentrate the energy on defence and repair responses. Alternatively, it can be also interpreted as the often observedaction of helminths to modify host immunity in its own interest. These results provide the first toolkit for future studiestowards understanding and management of this parasitosis.

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Oomycetes of the genus Saprolegnia are responsible for severe economic losses in freshwater aquaculture. Following the ban of malachite green in food fish production, the demand for new treatments pushes towards the selection of more safe and environment‐friendly products. In the present work, in vitro activity of ten chemicals and three commercial products was tested on different strains of Saprolegnia, using malachite green as reference compound. The compounds were screened in agar and in water to assess the minimum inhibitory concentration (MIC) and the minimum lethal concentration (MLC), respectively. Two strains of Saprolegnia parasitica and one isolate of Saprolegnia delica were tested in triplicate per each concentration. Among tested chemicals, benzoic acid showed the lowest MIC (100 ppm) followed by acetic acid, iodoacetic acid and copper sulphate (250 ppm). Sodium percarbonate was not effective at any tested concentration. Among commercial products, Virkon™S was effective in inhibiting the growth of the mycelium (MIC = MLC = 1,000 ppm). Actidrox® and Detarox® AP showed MIC = 5,000 and 1,000 ppm, respectively, while MLCs were 10‐fold lower than MICs, possibly due to a higher activity of these products in water. Similarly, a higher effectiveness in water was observed also for iodoacetic acid.

Check out all ParaFishControl publications here

The third ParaFishControl e-newsletter has now been published!

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