THE COMPLETE GENOME STRUCTURE AND PHYLOGENETIC RELATIONSHIP OF INFECTIOUS HEMATOPOIETIC NECROSIS VIRUS

Infectious hematopoietic necrosis virus (IHNV), a member of the family Rhabdoviridae, causes a severe disease with high mortality in salmoni d fish. The nucleotide sequence (11,131 bases) of the entire genome wa s determined for the pathogenic WRAC strain of IHNV from southern Idah o. This allowed detailed analysis of all 6 genes, the deduced amino ac id sequences of their encoded proteins, and important control motifs i ncluding leader, trailer and gene junction regions. Sequence analysis revealed that the 6 virus genes are located along the genome in the 3' to 5' order: nucleocapsid (N), polymerase-associated phosphoprotein ( P or M1), matrix protein (M or M2), surface glycoprotein (G), a unique non-virion protein (NV) and virus polymerase (L). The IHNV genome RNA was found to have highly complementary termini (15 of 16 nucleotides) . The gene junction regions display the highly conserved sequence UCUR UC(U)(7)RCCGUG(N)(4)CACR (in the vRNA sense), which includes the typic al rhabdovirus transcription termination/polyadenylation signal and a novel putative transcription initiation signal. Phylogenetic analysis of M, G and L protein sequences allowed insights into the evolutionary and taxonomic relationship of rhabdoviruses of fish relative to those of insects or mammals, and a broader sense of the relationship of non -segmented negative-strand RNA viruses. Based on these data, a new gen us, piscivirus, is proposed which will initially contain IHNV, viral h emorrhagic septicemia virus and Hirame rhabdovirus.