Survey on Betanodavirus in Wild Fish Species in the Turkish Coastlines of the Mediterranean Sea and Molecular Characterization: detecting different genotypes from different fish in different locations

Viral nervous necrosis is a viral disease caused by betanodavirus causing deaths and epidemics in wild or farmed sea fish, especially in juveniles. Betanodavirus has been detected in farmed European seabass and gilthead seabream in Turkey. However, there are no studies on the presence of betanodavirus in wildlife along the Turkish Mediterranean coast. This study aimed to investigate the presence of betanodavirus in wild fish along the Turkish coast of the Mediterranean and to characterize isolates using molecular tools. Hence, 400 fish belonging to 27 different wild species were caught and tested using real-time RT‒PCR. The betanodavirus genome was detected in red mullets (25/50) and garfish (2/4) and identified as RGNNV and RGNNV/SJNNV genotype, respectively according to partial genome sequencing of the RNA1 and RNA2 segments. Phylogenetic analysis showed that isolated viruses were similar to isolates collected from other parts of the Mediterranean Sea and China, India, and Japan. The results of the studies show that different genotypes are circulating in the studied region in different species. These findings indicates that more research on wildlife, both around the farm and in other regions, are needed to prevent spreading of the virus to aquaculture facilities.