THE FIRST OUTBREAK OF VIRAL ENCEPHALOPATHY AND RETINOPATHY IN FARMED SEA BASS (Dicentrarchus labrax) IN SLOVENIA

Abstract: Viral encephalopathy and retinopathy (VER) is considered a serious disease of several marine fish species, caused by RNA virus belonging to the family Nodaviridae, genus Betanodavirus. The spread almost worldwide causes significant losses among diseased fish. It characterised vacuolation central nervous system retina. In July 2018, behavioural abnormalities i.e. altered swimming, swirling vertical floating as well lethargy anorexia were observed in farmed sea bass (Dicentrarchus labrax) Gulf Piran (Slovenia), associated with mortality. initially occurred juvenile bass, but later market-sized also became affected. Diseased displayed ocular opacity multifocal skin ulceration on head. Emaciation some was evident. Histopathology revealed characteristic brain Performing RT-PCR RT-qPCR techniques, we have identified confirmed presence betanodavirus nucleic acid tissues. addition, concentrations causative agent VER spleen kidney did result significantly higher viral yield than expected. Phylogenetic analysis showed that Slovenian isolate belongs RGNNV species betanodaviruses. Based clinical signs, gross typical microscopic lesions results molecular analyses, can conclude from affected VER. To best our knowledge, this first report Slovenia.Key words: retinopathy; betanodavirus; bass; histopathology; PRVI IZBRUH VIRUSNE ENCEFALOPATIJE IN RETINOPATIJE PRI GOJENIH BRANCINIH V SLOVENIJI Izvleček: Virusna encefalopatija retinopatija je nevarna bolezen številnih vrst morskih rib, ki jo povzroča nevrotropni iz družine rod Bolezen razširjena skoraj po vsem svetu visok pogin okuženih rib. Zanjo so značilne vakuole v centralnem živčnem sistemu retini. Konec julija 2018 ribogojnici Piranskem zalivu pri brancinih opazili nepravilno plavanje, vrtenje postavljanje vertikalno smer ter letargijo neješčnost, brancini množično poginjali. se najprej pojavila mladicah, nato tudi konzumnih kategorijah brancinov. Obolele ribe imele sivo-motna očesna zrkla multifokalne kožne razjede na glavi, posamezne bile shujšane. S histopatološko preiskavo smo ugotovili možganih Z molekularnima metodama potrdili prisotnost nukleinske kisline betanodavirusa očesnem zrklu možganih. Koncentracije virusa, signifikantno višje od pričakovanih, vranici ledvicah. Na podlagi kliničnih znakov, makroskopskih tipičnih histopatoloških sprememb rezultatov molekularnih preiskav lahko zaključimo, da gojeni zboleli za Opisani izbruh prvi potrjeni primer te bolezni Sloveniji.Ključne besede: virusna retinopatija; brancin; histopatologija;