Comparative study of viral encephalopathy and retinopathy in juvenile sea bass Dicentrarchus labrax infected in different ways

Diseases of Aquatic Organisms

R. Thiéry¹  F. Baudin Laurencin¹  J. Jeffroy¹  A. Le Ven¹  S. Péducasse¹  J. Castric¹ 

关键词: Sea bass;    Viral encephalopathy and retinopathy;    Nodavirus;    Transmission;    Immunohistochemistry;    RT-PCR;   

DOI  :  10.3354/dao036011

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: The transmission of viral encephalopathy and retinopathy (VER) was investigated in juvenile sea bass (3 g) Dicentrarchus labrax by using cell culture supernatant (SSN-1 cell line) containing nodavirus. Five methods of infectionwere tested: intramuscular injection (IM), intraperitoneal injection (IP), oral infection, bath exposure and cohabitation of healthy fish with infected fish. Some differences were observed in time of disease onset and severity of symptoms depending on themode of infection used. Clinical symptoms such as whirling swimming and lethargic or hyperactive behaviour were generally reproduced, except for fish infected via oral and IP infection. First mortalities occurred 3 d after IM and IP infection and 6 dafter for the other modes of infection. Cumulative mortalities were also variable: 100% after IM infection, 10% after IP infection, 32% for bath exposure, 43% after cohabitation and 24% via oral infection. Histopathologically, vacuolation was observed inthe central nervous tissues and in the retina. The observed lesions were more or less severe depending on the mode of infection, the sampling time and the organs: lesions on the surviving fish (42 days post infection, d p.i.) seemed to be generally moreconspicuous in the retina than in the brain of the same fish. In most cases, the presence of nodavirus was confirmed in the same samples of brain and retina by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). The viruswas not detected in other organs examined. The present results suggest that 2 forms of VER can be induced: IM injection leads to an acute form (severe nervous disorders with high and fast mortality) whereas oral infection, bath exposure and cohabitationinduce a subacute form (less severe disorders and weak daily mortality). This experiment demonstrates experimentally induced horizontal transmission of VER in sea bass for the first time.

【 授权许可】

Unknown