Abstract
The production of the aquaculture industry has increased to be equal to that of the world fisheries in recent years. However, aquaculture production faces threats such as infectious diseases. Betanodaviruses induce a neurological disease that affects fish species worldwide and is caused by nervous necrosis virus (NNV). NNV has a nude capsid protecting a bipartite RNA genome that consists of molecules RNA1 and RNA2. Four NNV strains distributed worldwide are discriminated according to sequence homology of the capsid protein encoded by RNA2. Since its first description over 30 years ago, the virus has expanded and reassortant strains have appeared. Preventive treatments prioritize the RGNNV (red-spotted grouper nervous necrosis virus) strain that has the highest optimum temperature for replication and the broadest range of susceptible species. There is strong concern about the spreading of NNV in the mariculture industry through contaminated diet. To surveil natural reservoirs of NNV in the western Mediterranean Sea, we collected invertebrate species in 2015 in the Alboran Sea. We report the detection of the RGNNV strain in two species of cephalopod mollusks (Alloteuthis media and Abralia veranyi), and in one decapod crustacean (Plesionika heterocarpus). According to RNA2 sequences obtained from invertebrate species and reported to date in the Mediterranean Sea, the strain RGNNV is predominant in this semienclosed sea. Neither an ecosystem- nor host-driven distribution of RGNNV were observed in the Mediterranean basin.
Highlights
The disease caused by the betanodavirus Nervous necrosis virus (NNV) is known as viral encephalopathy and retinopathy (VER) or viral nervous necrosis (VNN), and was described over 30 years ago [3]
The present study aimed to contribute to the surveillance of reservoirs of nervous necrosis virus (NNV) in the unexplored western Mediterranean Sea, reporting non-natural reservoirs of the RGNNV strain in squid and shrimp species collected in the northern Alboran Sea (ALB)
Sequence similarity to reference sequences of the NNV genera Betanodavirus and to unclassified prawn nodaviruses indicates that all genomic fragments isolated from invertebrate animals in the ALB belong to the RGNNV strain, as illustrated by sequence clustering (Figure 2)
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Experimental infection of invertebrate cultures (Artemia and Rotifers) used as food in aquaculture has been reported [14], and recently, disease was recorded after feeding Senegalese sole larvae with NNV-infected. In European Atlantic and Mediterranean waters, the detection of NNV reservoirs in wild marine invertebrate species has been reported. The present study aimed to contribute to the surveillance of reservoirs of NNV in the unexplored western Mediterranean Sea, reporting non-natural reservoirs of the RGNNV strain in squid and shrimp species collected in the northern Alboran Sea (ALB). Viruses 2022, 14, 328 surveillance of reservoirs of NNV in the unexplored western Mediterranean Sea, reporting non-natural reservoirs of the RGNNV strain in squid and shrimp species collected in the northern Alboran Sea (ALB)
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