RETROVIRAL PROPERTIES INHERENT TO VIRAL ERYTHROCYTIC INFECTION IN SEABASS

The characterization of the aetiological agent of viral erythrocytic i nfection (VEI) of sea bass suggests a retroviral origin of the disease . RNA from viral erythrocytic infection virus (VEIV) and DNA from bloo d and organs of VEI-affected fish hybridized to a specific retrovirus cDNA probe. Sequences homologous to retrovirus genome were also detect ed in non-infected SBL cells (a sea bass cell line), however, Southern blot analysis showed that the DNA restriction patterns in VEI-affecte d erythrocytes differed from those of SBL cells. RNA-dependent DNA pol ymerase activity was detected in VEI-affected sea bass blood. This rev erse transcription was strongly Mn2+-dependent and is the first report of its occurrence in a marine fish and in fish blood samples. Nucleic acid sequences homologous to retrovirus RNA were detected in chromato graphic fractions exhibiting reverse transcriptase activity and the pr esence of virus-like particles, 125-150 mm in diameter. The density of VEIV in sucrose was 1.17-1.18 g/cm(3). The symptomatology of VEI is n ot far from those described for some retroviral diseases.