Detection of different Betanodavirus genotypes in wild fish from Spanish Atlantic coastal waters (Galicia, northwestern Spain)

Objective

The nervous necrosis virus (NNV; genus Betanodavirus) is an aquatic pathogen that is responsible for a neurological disease affecting marine fish. Despite its almost worldwide distribution, global warming could favor the spread of NNV to new areas, highlighting the importance of conducting epidemiological surveys on both wild and farmed marine fish species. In this study, we assessed NNV prevalence in wild fish caught along the Galician Atlantic coast.

Methods

In total, 1277 fish were analyzed by reverse transcription real-time polymerase chain reaction.

Result

Twenty two (1.72%) of those fish tested positive for NNV, including two species in which the pathogen had not yet been reported.

Conclusion

The reassortant RGNNV/SJNNV (red-spotted grouper NNV/striped jack NNV) was detected in 55% of NNV-positive individuals, while the remaining 45% harbored the SJNNV-type genome. Moreover, from European Pilchard Sardina pilchardus and Atlantic Mackerel Scomber scombrus, we isolated four reassortant strains that carried amino acid mutations at key sites related to NNV–host interaction.