Application of 3 techniques for diagnosing birnavirus infection in turbot

Three procedures for avoiding viral amplification by cell culture were evaluated for the diagnosis of birnavirus infections of turbot (Scophthalmus maximus) tissues. Immunodot assay using monoclonal and polyclonal antibodies was not satisfactory as a detection system because of false positive reactions. Although immunofluorescent assay of liver and kidney smears was an adequate method for a rapid diagnosis of the infection, blood smears from infected fish did not show higher levels of fluorescence than those from uninfected fish. However, the detection of birnavirus by polymerase chain reaction (PCR) amplification directly in fish tissues was successful and seems to be a promising system for the diagnosis of fish birnavirus.