Detection of different betanodavirus genotypes in wild fish from Spanish Atlantic coastal waters (Galicia, North-western Spain).

The Nervous Necrosis Virus (NNV) is an aquatic pathogen responsible for a neurological disease affecting marine fish. Despite its almost worldwide distribution, global warming could favour NNV spreading towards new areas, highlighting the importance of conducting epidemiological surveys on both wild and farmed marine fish species. In this study we have assessed NNV prevalence in wild fish caught along the Galician Atlantic coast. A total of 1,277 fish were analysed by reverse transcription real-time PCR (RT-rtPCR), of which 1.72% tested positive for NNV, including two species in which the pathogen had not yet been reported. The reassortant RGNNV/SJNNV was detected in 55% of these individuals, while the remaining 45% harboured SJNNV type genome. Moreover, 4 reassortant strains were isolated from pilchard and mackerel which carry amino acid mutations at key sites related to NNV-host interaction.