Three procedures for avoiding viral amplification by cell culture were
evaluated for the diagnosis of birnavirus infections of turbot (Scoph
thalmus maximus) tissues. Immunodot assay using monoclonal and polyclo
nal antibodies was not satisfactory as a detection system because of f
alse positive reactions. Although immunofluorescent assay of liver and
kidney smears was an adequate method for a rapid diagnosis of the inf
ection, blood smears from infected fish did not show higher levels of
fluorescence than those from uninfected fish. However, the detection o
f 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.