Investigation of fish encephalitis viruses (FEV) expression in marine fishes using DIG-labelled probes

Dicentrarchus labrax encephalitis virus (DIEV) genomic RNAs were partially cloned and used to identify and characterize the pattern of expression of viruses causing encephalitis in three different fish species, N2 and N12 probes either radioactively or DIG-labelled, hybridized to DlEV and Lares calcarifer encephalitis virus (LcEV) RNA1 and RNA2, respectively, but not to the genomic RNAs of two viruses from distinct families (Birnavindae, Picornaviridae). In situ hybridization confirmed that the pattern of expression of DlEV was highly restricted to the nervous tissues, A similar assay revealed the presence of a related virus in turbot and in shi drum exhibiting symptoms of encephalitis, although shi drum was not affected by nervous necrosis indicating some degree of relatedness between DlEV, LcEV and FEV infecting turbot and shi drum.