Diagnosis by reverse‐transcriptase polymerase chain reaction (RT‐PCR) amplification using previously published primers specific for the capsid protein gene of fish nodaviruses detected an isolate of sea bass, Dicentrarchus labrax L., nervous necrosis (SBNNV) from the French Mediterranean coast, but did not detect an isolate from the Atlantic coast. The capsid protein coding sequence of the nodavirus of both isolates was cloned...