DISTRIBUTION AND VARIATION OF NV GENES IN FISH RHABDOVIRUSES

The fish rhabdovirus infectious haematopoietic necrosis virus (IHNV) c ontains a non-virion (NV) gene between the glycoprotein (G) and polyme rase (L) genes on its RNA genome. The present study investigated three other fish rhabdovirus genomes and found that the NV gene of hirame r habdovirus is closely related to the NV of IHNV, whereas the viral hae morrhagic septicemia NV gene showed evidence of significant divergence . Most importantly, spring viraemia of carp virus, the only vesiculovi rus-like fish rhabdovirus examined, did not have an NV gene at its gen omic RNA G-L junction. These results suggest that the presence of an N V gene is characteristic of the unassigned fish rhabdovirus subgroup p reviously classified as lyssaviruses, and that the NV gene is not esse ntial for replication in fish cells per se, since it is absent in a ve siculovirus-like fish rhabdovirus.