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

2021 ◽  
Vol 58 (4) ◽  
Author(s):  
Rosvita Sitar ◽  
Tanja Švara ◽  
Aleksandra Grilc Fajfar ◽  
Sabina Šturm ◽  
Marko Cvetko ◽  
...  
Keyword(s):  
Rna Virus ◽  
Clinical Signs ◽  
Dicentrarchus Labrax ◽  
Sea Bass ◽  
Rt Pcr ◽  
Viral Yield ◽  
Diseased Fish ◽  
The Central Nervous System ◽  
Serious Disease ◽  
Viral Encephalopathy And Retinopathy

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

scholarly journals Isolation, characterization and sequence determination of Noda virus from sea bass (Dicentrarchus labraxL.) reared in freshwater and marine facilities in Greece

2017 ◽  
Vol 56 (2) ◽  
pp. 105
Author(s):  
E. XYLOURI (Ε. ΞΥΛΟΥΡΗ) ◽  
J. KOTZAMANIS (Ι. ΚΟΤΖΑΜΑΝΗΣ) ◽  
F. ATHANASSOPOULOU (ΑΘΑΝΑΣΟΠΟΥΛΟΥ Φ.) ◽  
L. DONG ◽  
A. ARGYROKASTRITIS (ΑΛ. ΑΡΓΥΡΟΚΑΣΤΡΙΤΗΣ) ◽  
...  
Keyword(s):  
Clinical Symptoms ◽  
Dicentrarchus Labrax ◽  
Sea Bass ◽  
Rt Pcr ◽  
Sequence Determination ◽  
Tissue Samples ◽  
Diseased Fish ◽  
Polymerase Chain ◽  
Virus Isolates

The present study aims το characterize Noda virus isolates from freshwater and marine fish, specifically from species Dicentrarchus labrax (sea bass). Previous works reported the detection of Noda virus only by using PCR, in cultured Dicentrarchus labrax showing clinical symptoms. Here we describe the isolation of Noda virus from symptomatic sea bass cultured in sea and freshwater facilities in Greece. The virus was isolated in the continuous cell line SSN -1, exhibiting characteristic cytopathic effect, vacuolation and degeneration of the monolayer. In parallel, in all cerebral tissue samples isolated from infected individuals, a 255 bp viral fragment has been detected, using Reverse Transcription - Polymerase Chain Reaction (RT-PCR) and nested PCR. Comparison of the amplified sequence was detected in diseased fish in European farms and in other piscine species revealed a high nucleotide homology.

scholarly journals Rickettsia-like organisms (R.L.O.) infections of fin-fish

2017 ◽  
Vol 55 (2) ◽  
pp. 165 ◽  
Author(s):  
F. ATHANASSOPOULOU (Φ. ΑΘΑΝΑΣΟΠΟΥΛΟΥ) ◽  
E. KARAGOUNI (ΚΑΡΑΓΚΟΥΝΗ Ε.)
Keyword(s):  
Dicentrarchus Labrax ◽  
Sea Bass ◽  
Olfactory Nerve ◽  
Internal Organs ◽  
European Sea Bass ◽  
Salmonid Species ◽  
Diseased Fish ◽  
The Brain ◽  
Mass Mortalities ◽  
Of Greece

Rickettsia-like organisms (R.L.O.) infections of finfish have been reported in several salmonid and non-salmonid species in both fresh and seawater since 1939. This organism was not considered of economical importance to the global fin-fish aquaculture industry until Piscirickettsia salmonis was confirmed as the etiology agent of mass mortalities in the Chile during the 1990's. All cultured salmonid species can be infected by this intracellular bacteria and in diseased fish it may provoke a systemic response affecting most internal organs, but preferentially targeting the liver.For other R.L.O's the pathology may vary depending on both the imunogenicity of the R.L.O. and the species offish affected; eg, R.L.O. infections of the Hawaiian tilapia result in a systemic granulomatous inflammatory response. Initial published reports on R.L.O's affecting cultured juvenile sea bass (Dicentrarchus labrax) were described from sea-cages, at rearing temperatures ranging from 12-15°C, in the Mediterranean off the coast of France. In this outbreak the reported pathology was restricted to the mesencephalic regions of the brain. Subsequendy, the organism was identified from cultured sea bass of the coast of Greece, with moribund fish showing similar pathology; i.e brain, olfactory nerve and internal organs inflammation. These samples were preliminarily screened by immunohistochemistry and found to cross react with antisera to P. salmonis. This finding was also confirmed by demonstrating antigenic similarities between P. salmonis and European sea bass R.L.O. isolates from Greece. Recendy, a systemic type of the disease was demonstrated by histopathology in juvenile cultured juvenile sea bass. The meningitis, as well as other internal lesions affecting sea bass, is nearly identical to that seen in for R.L.O. infected Adantic salmon from British Columbia, Canada. Similar lesions have been noted for piscirickettsiosis in both Chilean and Eastern Canadian outbreaks: i.e liver, pancreas, retina, brain stem, meninges and the lamina propria of intestine.

Quantitative immunoenzymatic detection of viral encephalopathy and retinopathy virus (betanodavirus) in sea bass Dicentrarchus labrax

2015 ◽  
Vol 39 (7) ◽  
pp. 821-831 ◽  
Author(s):  
N Nuñez-Ortiz ◽  
V Stocchi ◽  
A Toffan ◽  
F Pascoli ◽  
N Sood ◽  
...  
Keyword(s):  
Dicentrarchus Labrax ◽  
Sea Bass ◽  
Viral Encephalopathy And Retinopathy

scholarly journals Summer Mortality Syndrome Affecting Cultured European Seabass at Kafrelsheikh Province, Egypt

2021 ◽  
Vol 8 ◽  
Author(s):  
Nadia Gabr Ali ◽  
Asmaa Mahmoud El-Nokrashy ◽  
Mofeed Yousef Gouda ◽  
Ibrahim Mohamed Aboyadak
Keyword(s):  
Mortality Rate ◽  
Water Temperature ◽  
Clinical Signs ◽  
Dicentrarchus Labrax ◽  
Infected Fish ◽  
Bacterial Isolates ◽  
Isolation And Identification ◽  
European Seabass ◽  
Summer Mortality ◽  
Diseased Fish

The present work aimed to investigate the causes of summer mortality syndrome affecting cultured European seabass (Dicentrarchus labrax) by examining physiochemical farm water characteristics, isolation, and identification of recovered bacterial pathogens from diseased fish studying the effect of water temperature on stress biomarkers and disease severity. Studied water parameters were normal except ammonia and dissolved oxygen was higher and lower than the standard value. Sixty-two bacterial isolates were recovered from moribund fish and identified as 31 Vibrio fluvialis, 23 Pseudomonas aeruginosa and 8 Staphylococcus aureus isolates. The calculated LD50 of V. fluvialis, P. aeruginosa and S. aureus for D. labrax fingerlings were 4.67 × 107, 2.37 × 106 and 1.38 × 107, respectively. There was a direct correlation between water temperature and mortality rate of fish challenged with V. fluvialis as the mortality rate was 44.44, 50, 66.66, and 83.33% for fish maintained at 27, 30, 33, and 36°C. Plasma cortisol, superoxide dismutase, catalase and malondialdehyde significantly increased when the water temperature exceeded 30°C. The experimentally infected fish showed similar clinical signs and postmortem lesions of naturally diseased fish with no boundary between different pathogens. Antibiogram test indicated that florfenicol was the most effective antibiotic against all the recovered bacterial isolates while all isolates resisted sulfamethoxazole-trimethoprim. Massive degenerative changes observed in the hepatopancreas, posterior kidney and gill tissues of experimentally infected fish.

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