The first detection of betanodavirus reassortant genotype (RGNNV/SJNNV) isolated from gilthead sea bream (Sparus aurata) in the Turkish coastlines: The importance of screening and monitoring studies for identifying the source of the infection

Abstract

Viral nervous necrosis (VNN), caused by betanodaviruses belonging to the Nodaviridae family, poses a significant threat to aquaculture production, sustainability and development (Costa & Thompson, 2016;Thiéry et al., 2011;Toffan et al., 2017). It has been reported that 177 marine species are susceptible to betanodaviruses, and epizootic outbreaks have been reported in 62 marine species (Bandín & Souto, 2020). The most commonly affected species are the European sea bass (ESB), Asian sea bass, groupers, Japanese flounder, barfin flounder and flatfish; however, other marine fish are also susceptible (Bandín and Souto, 2020;Munday et al., 2002;Sano et al., 2011). Outbreaks related to betanodavirus in gilthead sea bream (GSB) have also been reported (Bitchava et al., 2007;Comps & Raymond, 1996; Volpe et al., 2020), although information regarding betanodavirus infection in GSB has historically been scarce.Following recent reports of GSB deaths related to betanodavirus

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

“…In ongoing studies, NNV has been detected frequently in sea bass and the RGNNV genotype was identified (Kalaycı et al 2016;Kaplan and Karaoğlu 2021). The RGNNV/SJNNV genotype was also isolated from asymptomatic sea bream only in the Aegean Sea (Kaplan, Pekmez, Cagirgan, et al 2022).…”

“…Rather than being species-specific, genotypes require a water temperature at which they develop optimally (Costa and Thompson 2016;Mori et al 2005). Because of the segmented nature of the virus, the formation of reassortant strains has thus far been identified in the SJNNV and RGNNV genotypes, and RGNNV/ SJNNV or SJNNV/RGNNV reassortants have been reported many times in sea bass, sea bream and sole (Bitchava et al 2019;He and Teng 2015;Kaplan, Pekmez, Cagirgan, et al 2022;Toffan et al 2017;Volpe et al 2020).…”

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

“…2022; Kaplan et al. 2022). In contrast, our results indicate that approximately half of the NNV‐positive individuals caught in Galician coastal waters were RGNNV/SJNNV reassortants (55%), and the other half were the SJNNV type (45%).…”

Reassortant viruses threatening fish aquaculture

“…20 Conversely, RGNNV/SJNNV reassortant strains (Table 1) are widespread and have been isolated from farmed European sea bass, gilthead seabream, Senegalese sole (Solea senegalensis) and common sole (Solea solea) or even wild Mediterranean horse mackerel (Trachurus mediterraneus). 14,[16][17][18][19]21 Beyond its incidence in South Europe, RGNNV/SJNNV strains have been recently identified in gilthead seabream from Tunisia and Turkey rounding the Mediterranean coast, 22,23 as well as in farmed hybrid groupers (Epinephelus fuscoguttatus  Epinephelus lanceolatus) in Malasya (Figure 2). 15 The rapid spread of these reassortant strains underlines the urgent necessity of new preventive measures to control the spread of the virus.…”