RESUMO
The fish rhabdovirus infectious haematopoietic necrosis virus (IHNV) contains a non-virion (NV) gene between the glycoprotein (G) and polymerase (L) genes on its RNA genome. The present study investigated three other fish rhabdovirus genomes and found that the NV gene of hirame rhabdovirus is closely related to the NV of IHNV, whereas the viral haemorrhagic septicemia NV gene showed evidence of significant divergence. Most importantly, spring viraemia of carp virus, the only vesiculovirus-like fish rhabdovirus examined, did not have an NV gene at its genomic RNA G-L junction. These results suggest that the presence of an NV gene is characteristic of the unassigned fish rhabdovirus subgroup previously classified as lyssaviruses, and that the NV gene is not essential for replication in fish cells per se, since it is absent in a vesiculovirus-like fish rhabdovirus.
Assuntos
Doenças dos Peixes , Variação Genética , Infecções por Rhabdoviridae/veterinária , Rhabdoviridae/genética , Proteínas Virais/genética , Sequência de Aminoácidos , Animais , Carpas , Mapeamento Cromossômico , Genoma Viral , Dados de Sequência Molecular , Peso Molecular , Fases de Leitura Aberta , Rhabdoviridae/patogenicidade , Rhabdoviridae/fisiologia , Infecções por Rhabdoviridae/virologia , Salmonidae , Homologia de Sequência de Aminoácidos , Proteínas Virais/biossíntese , Proteínas Virais/química , Viremia/veterinária , Viremia/virologia , Replicação ViralRESUMO
The nucleotide sequences of the glycoprotein genes and all of the internal gene junctions of the fish pathogenic rhabdoviruses spring viremia of carp virus (SVCV) and hirame rhabdovirus (HIRRV) have been determined from cDNA clones generated from viral genomic RNA. The SVCV glycoprotein gene sequence is 1588 nucleotides (nt) long and encodes a 509 amino acid (aa) protein. The HIRRV glycoprotein gene sequence comprises 1612 nt, coding for a 508 aa protein. In sequence comparisons of 15 rhabdovirus glycoproteins, the SVCV glycoprotein gene showed the highest amino acid sequence identity (31.2-33.2%) with vesicular stomatitis New Jersey virus (VSNJV), Chandipura virus (CHPV) and vesicular stomatitis Indiana virus (VSIV). The HIRRV glycoprotein gene showed a very high amino acid sequence identity (74.3%) with the glycoprotein gene of another fish pathogenic rhabdovirus, infectious hematopoietic necrosis virus (IHNV), but no significant similarity with glycoproteins of VSIV or rabies virus (RABV). In phylogenetic analyses SVCV was grouped consistently with VSIV, VSNJV and CHPV in the Vesiculovirus genus of Rhabdoviridae. The fish rhabdoviruses HIRRV, IHNV and viral hemorrhagic septicemia virus (VHSV) showed close relationships with each other, but only very distant relationships with mammalian rhabdoviruses. The gene junctions are highly conserved between SVCV and VSIV, well conserved between IHNV and HIRRV, but not conserved between HIRRV/IHNV and RABV. Based on the combined results we suggest that the fish lyssa-type rhabdoviruses HIRRV, IHNV and VHSV may be grouped in their own genus within the family Rhabdoviridae. Aquarhabdovirus has been proposed for the name of this new genus.
Assuntos
Carpas/virologia , Peixes/virologia , Glicoproteínas/genética , Rhabdoviridae/genética , Proteínas Virais/genética , Animais , Sequência de Bases , Linhagem Celular , Clonagem Molecular , DNA Complementar , Dados de Sequência Molecular , Filogenia , Rhabdoviridae/metabolismo , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , ViremiaRESUMO
Infectious hematopoietic necrosis virus (IHNV) is a rhabdovirus which causes a serious disease in salmonid fish. The T1 ribonuclease fingerprinting method was used to compare the RNA genomes of 26 isolates of IHNV recovered from sockeye salmon (Oncorhynchus nerka), chinook salmon (O. tshawytscha), and steelhead trout (O. mykiss) throughout the enzootic portion of western North America. Most of the isolates analyzed in this study were from a single year (1987) to limit time of isolation as a source of genetic variation. In addition, isolates from different years collected at three sites were analyzed to investigate genetic drift or evolution of IHNV within specific locations. All of the isolates examined by T1 fingerprint analysis contained less than a 50% variation in spot location and were represented by a single fingerprint group. The observed variation was estimated to correspond to less than 5% variation in the nucleic acid sequence. However, sufficient variation was detected to separate the isolates into four subgroups which appeared to correlate to different geographic regions. Host species appeared not to be a significant source of variation. The evolutionary and epizootiologic significance of these findings and their relationship to other evidence of genetic variation in IHNV isolates are discussed.
Assuntos
Variação Genética , Rhabdoviridae/genética , Animais , Impressões Digitais de DNA , RNA Viral , Rhabdoviridae/classificação , Rhabdoviridae/isolamento & purificação , Salmão/virologia , Truta/virologiaRESUMO
The genomic RNA of the fish rhabdovirus infectious hematopoietic necrosis virus (IHNV) contains a small NV gene which is not present in any other rhabdoviruses characterized to date. We have constructed a plasmid which carries a full length cDNA copy of the IHNV NV gene between 2 RNA polymerase promoters such that plus-sense and minus-sense RNA transcripts of the IHNV NV gene can be synthesized. These were used to develop an RNase protection assay which was capable of detecting as little as 1-5 ng of NV mRNA or genomic RNA. RNA from tissue culture cells infected with 3 different strains of IHNV showed distinct, diagnostic cleavage patterns reflecting sequence variation in their NV genes.
