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EXPERT TOPIC

Figure 7- Blood sample collected from a juvenile (IMR, Norway)

protein (GFP), it could be visualised by fluorescence microscopy that Artemia filtered efficiently and ingested these microbes, and thereby the harboring recombinant protein. Artemia ingested recombinant Nodavirus capsid protein expressed by the various systems, which could be confirmed by immunoblotting. The recombinant capsid protein expressed by the different system was then fed to Artemia, which were fed to Atlantic halibut larvae at 100 dph. Ten weeks later, the juveniles in all treatment groups were challenged by an i.p. injection (see figure 7) with Nodavirus to check for efficacy. The challenged fish were terminated eight weeks post-challenge and tested for the presence of Nodavirus in the brain by realtime RT-PCR targeting the viral RNA2-segment. No significant difference could be seen between the different treatment groups, including the group with recombinant protein that has shown protection earlier. This indicates that the size of the fish and the need to sort fish to minimise huge variation between individuals in different phases at

ATLANTIC HALIBUT

the time of vaccination have its inherent limitations and should be carefully considered. In conclusion, although it has been shown that Artemia will take up and accumulate the various forms of recombinant Nodavirus capsid proteins and act as a vector for oral delivery to larvae of Atlantic halibut, the challenge experiments indicate that this strategy of antigen delivery does not induce protection against Nodavirus infection, at least under the conditions used in this study. A technical production manual has been produced for Atlantic halibut and can be downloaded from the project’s website at www. diversifyfish.eu. This 5-year-long project (2013-2018) has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration (KBBE2013-07 single stage, GA 603121, DIVERSIFY). The consortium includes 38 partners from 12 European countries –including nine SMEs, two Large Enterprises, five professional associations and one Consumer NGO- and was coordinated by the Hellenic Centre for Marine Research, Greece. www.diversifyfish.eu In our previous article on the DIVERSIFY project dealing with MEAGRE, the author’s affiliation are: Alicia Estévez, IRTA, Spain Daniel Montero, FCPCT, Spain Constatinos C Mylonas, HCMR, Greece Rocio Robles, Ctaqua, Spain Gemma Tacken, SWR, the Netherlands Luis Guerrero, IRTA, Spain Neil Duncan, IRTA, Spain Pantelis Katharios, HCMR, Greece.

TA S T E F O R P E R F O R M A N C E

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International Aquafeed - May 2019 | 49

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MAY 2019 - International Aquafeed magazine  

MAY 2019 - International Aquafeed magazine