Abstract
The nervous necrosis virus (NNV) leads to viral encephalopathy and retinopathy (VER) disease in more than 170 fish species, mainly from marine habitats. It replicates in the central nervous tissues, reaching up to 100% mortalities after a few days of infection, mainly in the larvae and juvenile stages. This is continuously spreading and affecting more species, both wild and cultured, posing a risk to the development of the aquaculture industry. In the Mediterranean Sea, it mainly affects European sea bass (Dicentrarchus labrax) and some grouper species (Epinephelus spp.). Interestingly, in the gilthead seabream (Sparus aurata), typically resistant to common NNV strains, great mortalities in hatcheries associated with typical clinical signs of VER have been confirmed to be caused by RGNNV/SJNNV reassortants. Thus, we have evaluated the susceptibility of seabream larvae to either RGNNV/SJNNV or SJNNV/RGNNV reassortants, as well as the larval immunity. Based on our results we can conclude that: (i) gilthead seabream larvae are susceptible to infection with both NNV reassortant genotypes, but mainly to RGNNV/SJNNV; (ii) virus replicated and infective particles were isolated; (iii) larval immunity was correlated with larval survival; and (iv) larval resistance and immunity were correlated with age of the larvae. Further investigations should be carried out to ascertain the risks of these new pathogens to Mediterranean larviculture.
Author Contributions
Methodology and investigation, M.Á.G.-Á., L.C., J.C.C-S., C.G.-F., M.A., E.C.-P.; software and data curation, M.Á.G.-Á. and A.C.; conceptualization and supervision, E.C.-P. and A.C.; writing—original draft preparation, M.Á.G.-Á.; writing—review and editing, E.C.-P., M.Á.G.-Á., M.A., M.Á.E. and A.C.; project administration and funding acquisition, M.A., E.C.-P., A.C. All authors have read and agreed to the published version of the manuscript.
Funding
This work was funded by Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación [MCIN/AEI/10.13039/501100011033, grant PID2019-105522GB-I00 to AC], Ministerio de Economía y Competitividad and FEDER [grant RTI2018-096625-B-C33 to ECP] and Fundación Séneca, Grupo de Excelencia de la Región de Murcia [19883/GERM/15].
Institutional Review Board Statement
All specimens were handled in accordance with the Guidelines of the European Union Council (2010/63/EU) and the optimal zootechnical protocols of the Centro Oceanográfico de Murcia (IEO-CSIC, REGA ES300261040017), the Bioethical Committee of the IEO-CSIC and the approval of the Ministry of Water, Agriculture and Environment of the Autonomous Community Region of Murcia (Permit number A13200602).
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
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