Sea bream Sparus aurata, an asymptomatic contagious fish host for nodavirus

During an epidemiological survey of viral encephalopathy and retinopathy (VER) in diseased sea bass Dicentrarchus labrax, a nodavirus isolate was recovered from net pen-reared sea bream Sparus aurata harboured in the same farming premises. After the virus was isolated and identified by immunofluorescence on SSN-1 cells, sequence analysis with a PCR product from the T4 region of the capsid protein gene indicated that the virus shared 100% identity with a pathogenic virus strain isolated from sea bass. Infection trials demonstrated the pathogenicity of the sea bream virus isolate for juvenile sea bass whereas sea bream infected with the same virus isolate remained asymptomatic even following intramuscular injection of virus. Nevertheless, the sea bream appeared to be a potential carrier of nodavirus, as juvenile sea bass became infected when maintained in a tank containing experimentally contaminated sea bream.