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At least 19 recordsLinked to original sources

PubMed2005

Yunnan orbivirus, a new orbivirus species isolated from Culex tritaeniorhynchus mosquitoes in China.

An orbivirus designated Yunnan orbivirus (YUOV) was isolated from Culex tritaeniorhynchus mosquitoes collected in the Yunnan province of China. Electron microscopy showed particles with typical orbivirus morphology. The YUOV genome was sequenced completely and compared with previously characterized orbivirus genomes. Significant identity scores were detected between proteins encoded by the segments (Seg-1 to Seg-10) of YUOV and those encoded by their homologues in insect-borne and tick-borne orbiviruses. Analysis of VP1 (Pol) and VP2 (T2, which correlates with the virus serogroup) indicated that YUOV is a new species of the genus Orbivirus that is unrelated to the other insect-borne orbiviruses. The replication of YUOV in mosquito cell lines was restricted to Aedes albopictus cells and the virus failed to replicate in mammalian cell lines. However, intraperitoneal injection of virus into naïve mice resulted in productive, non-lethal virus replication and viraemia. Infected mice developed serum neutralizing antibodies and were protected against a new infection challenge. Sequence analysis of clones from the segments encoding outer coat proteins (Seg-3 and Seg-6) of YUOV recovered from mouse blood did not show significant changes in the sequences. The availability of the complete genome sequence will facilitate the development of sequence-specific PCR assays for the study of YUOV epidemiology in the field.

Animals↗

PubMed2001

Complete sequence characterization of the genome of the St Croix River virus, a new orbivirus isolated from cells of Ixodes scapularis.

An orbivirus identified as St Croix River virus (SCRV) was isolated from cells of Ixodes scapularis ticks. Electron microscopy showed particles with typical orbivirus morphology. The SCRV genome was sequenced completely and compared to previously characterized orbivirus genomes. Significant identity scores (21-38%) were detected between proteins encoded by segments S1, S2, S4, S5, S6, S8, S9 and S10 of SCRV and those encoded by segments S1, S3, S4, S5, S6, S7, S9 and S10, respectively, of Bluetongue virus (BTV), the prototype orbivirus species. The protein encoded by SCRV genome segment 3 (VP3) is thought to be the equivalent of VP2 of BTV. Segment 7 encodes a protein homologous to non-structural protein NS2(ViP) of BTV. Analysis of VP1(Pol) (segment 1) shows that SCRV is an orbivirus, distantly related to the other sequenced species. Blot hybridizations and sequence comparisons of the conserved protein encoded by genome segment 2 (the T2 subcore shell protein) with previously identified orbiviruses confirm that SCRV is a distinct orbivirus species, unrelated to another tick-borne species, Great Island virus. The presence of SCRV in cells prepared from tick eggs suggests that transovarial transmission of SCRV may occur in ticks.

Animals↗

PubMed1995

Enhanced replication of orbiviruses in bovine testicle cells infected with bovine viral diarrhoea virus.

Bovine testicle (BT) cells infected with non-cytopathogenic (NCP) bovine viral diarrhoea virus (BVDV) developed cytopathogenic effect (CPE) after superinfection with 7 Orbiviruses, whereas no CPE was induced by them in the absence of NCP BVDV infection. The CPE was accompanied by the enhanced replication of Orbiviruses. Seven of 10 strains of NCP BVDV induced the enhanced replication of Ibaraki virus, a member of Orbivirus. These 7 strains of NCP BVDV were END phenomenon positive. In contrast, the absence of CPE and the suppression of growth of Ibaraki virus were seen in BT cells infected with the other 3 strains which were END phenomenon negative. The END phenomenon negative viruses were different markedly from the END phenomenon positive viruses with respect to interactions with Orbivirus. The mechanism of the enhanced replication of Orbivirus seems to be explained with the suppression by the END phenomenon positive NCP BVDV to the interferon production of Orbivirus in BT cells.

Animals↗

PubMed1991

Genetic relatedness of two new Orbivirus serogroups: Orungo and Lebombo.

Orungo and Lebombo orbivirus isolates were examined for their intra- and intergroup genetic relatedness by blot hybridization and gene reassortment; blot hybridization was also used to examine the relatedness of selected Orungo and Lebombo isolates to known orbiviruses. Among the Orungo isolates, greater than 74% sequence similarity was shown in the majority of their genes. Gene 2 was the most divergent gene, with four unique types identified, and genes 5, 6 and 10 were variant among the isolates. Plaque reduction neutralization tests revealed at least four serotypes, a result which correlated with the hybridization data. Gene reassortment was shown between two representative Orungo isolates. Among the Lebombo isolates, two hybridization types were identified between which gene reassortment was demonstrated. Unique genes were not shown, whereas genes 2, 5 and 10 exhibited minor sequence variability. Geographic distribution correlated with relatedness among the Lebombo isolates, which was not the case among the Orungo isolates. Orungo and Lebombo viruses did not cross-hybridize or reassort their genes in vitro, in intergroup studies. In blot hybridization tests of Orungo and Lebombo isolates with known orbivirus serogroups and ungrouped orbiviruses, no strong cross-hybridization was seen. These results demonstrate that Orungo and Lebombo are distinct from each other and from other orbiviruses, and should therefore be recognized as two new Orbivirus serogroups.

Autoradiography↗

PubMedDate not supplied

The orbivirus genus. Diversity, structure, replication and phylogenetic relationships.

The general properties of the orbiviruses have been examined at the physical, structural and molecular level. At the structural level, the orbiviruses (with the exception of the Kemerovo serogroup) appear similar. The replicative events are also similar, however differences in the ultrastructure of virus-specific structures and their association with components of the host cell have been observed. Further research in this area may be used to differentiate between the serogroups and even some serotypes, of orbiviruses. At the molecular level the properties of the genome can be used to determine relationships between members of the orbivirus genus. These relationships are revealed using a variety of techniques including serology and gene sequence analysis. Not only are the different serological responses to gene products present in the mature virus particle used for differential diagnosis, but the gene sequences themselves can also be utilized. Understanding of the relationships between these viruses is progressing to the point that insights into orbivirus molecular epidemiology is now possible.

Animals↗

PubMed1987

The complete nucleotide sequence of bluetongue virus serotype 1 RNA3 and a comparison with other geographic serotypes from Australia, South Africa and the United States of America, and with other orbivirus isolates.

The sequence of the RNA segment 3 of bluetongue virus (BTV) serotype 1 from Australia is presented along with its deduced amino acid sequence. DNA copies of this genome segment were inserted either into the E. coli plasmid pBR322 by homopolymeric tailing or by direct insertion of double-stranded DNA fragments generated by restriction endonuclease cleavage into the appropriate M13 bacteriophage vectors (Vieira, J. and Messing, J., 1982, Gene 19, 259-268). Direct comparisons were made to the nucleotide sequence data of Purdy, M. et al., 1984 (J. Virol. 51, 754-759) and Ghiasi, H. et al., 1985 (Virus Res. 3, 181-190) for the United States of America (US) isolates of BTV, serotypes 10 and 17, respectively. A method for the rapid cloning, sequencing and alignment of orbivirus RNA 3 segments was utilised to compare other geographical isolates of BTV, as well as those of other orbivirus serotypes, in particular, epizootic haemorrhagic disease of deer virus (EHDV) and Warrego. The comparison of this sequence data reveals that BTV isolates can be separated into distinct geographical types which in turn are distinct from the other orbivirus isolates studied. The sequence conservation at the amino acid level for the gene product of RNA3 (VP3) does not enable distinctions to be made amongst the BTV isolates at a geographical level, but does afford easy distinction into the different orbivirus groups. A possible evolutionary schematic is presented for the orbiviruses studied.

Amino Acid Sequence↗

PubMed1995

Comparison of the non-structural protein, NS1, of tick-borne and insect-borne orbiviruses.

The nucleotide sequence of RNA segment 6 of Broadhaven virus (BRDV), a tick-borne orbivirus, was determined principally from two overlapping cDNA clones and RNA end sequence analysis. The genome segment is 1714 base pairs in length and has a coding capacity for a protein of 537 amino acids, having a net charge of +4.0 at neutral pH. Comparison of the predicted amino acid sequence of BRDV RNA segment 6 with the NS1 sequence of insect-borne orbiviruses, bluetongue virus (BTV), African horse sickness virus (AHSV) and epizootic haemorrhagic disease virus (EHDV) of deer, revealed amino acid identities of 21, 22 and 21%, respectively. This compares with amino acid identities of 31 to 50% between the NS1 proteins of these gnat-transmitted orbiviruses. A recombinant baculovirus was produced containing a full-length clone of BRDV segment 6, which expressed a protein of 61 kD in infected Spodoptera frugiperda cells. Like other orbivirus NS1 proteins the expressed protein formed tubules similar to those produced in BRDV-infected BHK21 cells.

Amino Acid Sequence↗

PubMed1996

Characterisation of Wongorr virus, an Australian orbivirus.

Sequence analyses of VP3 gene segments of Wongorr virus isolates from the Northern Territory of Australia were compared with the cognate gene segments from Picola and Paroo River viruses. Previous serological investigations had demonstrated some relationships between these viruses, however VP3 gene sequence and phylogenetic analyses placed these viruses within the same serogroup which was distinct from other described orbivirus serogroups. A polymerase chain reaction (PCR) was developed for the detection of this serogroup and used to identify and determine partial sequence data for other isolates of the virus. Wongorr virus and the other tick and mosquito-borne orbiviruses (Kemerovo and Corriparta), were more closely related than the Culicoides transmitted orbiviruses, such as bluetongue (BTV) and African horse sickness virus (AHSV) which were shown to be on a separate branch of the orbivirus phylogenetic tree.

Aedes↗

PubMed1984

Characterization of Nugget virus, a serotype of the Kemerovo group of orbiviruses.

The genome of Nugget virus, a serotype of the Kemerovo group of orbiviruses, consists of 10 segments of double-stranded RNA. The properties of the virus are consistent with its classification as an orbivirus , but the unusual patterns of separation of viral RNA and polypeptides compared with that reported for most other orbiviruses suggests the possibility of heterogeneity within the genus Orbivirus .

Electrophoresis, Polyacrylamide Gel↗

PubMed1996

Orbivirus structure and assembly.

Orbiviruses (Reoviridae family) are complex nonenveloped RNA viruses with seven structural proteins and a RNA genome consisting of 10 variously sized double-stranded RNA segments. Significant advances in orbivirus research have been made in recent years through the use of gene manipulation techniques coupled with the baculovirus expression system. Several orbivirus proteins have yielded to crystallization and X-ray crystallographic structure determination and, when combined with the three-dimensional image reconstruction of virion particles and cores obtained by cryoelectron microscopy, considerable insight has been gained into the intricate organization and topography of the individual viral components. Formal identification of the sites of interaction has been obtained through protein-protein interaction studies on the components of the virion particle, including those that are involved in capsid assembly. Finally, a beginning of the understanding of the sequence of assembly events has also been obtained.

Animals↗

PubMed2006

Structural studies on orbivirus proteins and particles.

X-ray and electron microscopy analysis of Bluetongue virus (BTV), the type species of the Orbivirus genus within the family Reoviridae, have revealed various aspects of the organisation and structure of the proteins that form the viral capsid. Orbiviruses have a segmented dsRNA genome, which imposes constraints on their structure and life cycle. The atomic structure of the BTV core particle, the key viral component which transcribes the viral mRNA within the cell cytoplasm, revealed the architecture and assembly of the major core proteins VP7 and VP3. In addition, these studies formed the basis for a plausible model for the organisation of the dsRNA viral genome and the arrangement of the viral transcriptase complex (composed of the RNA-dependent RNA polymerase, the viral capping enzyme and RNA helicase) that resides within the core particle. Electron cryo-microscopy of the viral particle has shown how the two viral proteins VP2 and VP5 are arranged to form the outer capsid, with distinct packing arrangements between them and the core protein VP7. By comparison of the outer capsid proteins of orbiviruses with those of other nonturreted members of the family Reoviridae, we are able to propose a more detailed model of these structures and possible mechanisms for cell entry. Further structural results are also discussed including the atomic structure of an N-terminal domain of nonstructural protein NS2, a protein involved in virus genome assembly and morphogenesis.

Biological Transport↗

PubMed1994

A rapid indirect ELISA for the serogrouping of Australian orbiviruses.

This communication describes the development and evaluation of a simple and rapid method for the classification of Australian orbiviruses into one of seven established serogroups (i.e. bluetongue, epizootic haemorrhagic disease of deer, Palyam, Eubenangee, Corriparta, Wallal, Warrego) or an 'ungrouped' category. The Australian orbivirus serogrouping ELISA (SG-ELISA) utilised a sodium deoxycholate-treated cell lysate preparation from infected BHK cells which was subsequently probed in an indirect ELISA format with polyclonal antibodies representative of each serogroup. Bound immunoglobulin was detected by the use of a recombinant streptococcal protein G-HRPO conjugate and subsequent reaction with the chromogenic substrate. All reference orbiviruses tested in the SG-ELISA were identified and were in agreement with the serogroups originally designated. Minimal inter-serogroup cross-reactions were observed. One-way cross-reactions were observed between Warrego and Mitchell River viruses.

Animals↗

PubMed1992

Comparison of the major structural core proteins of tick-borne and Culicoides-borne orbiviruses.

Comparison of sequence data for Broadhaven (BRD) virus, a tick-borne orbivirus, and bluetongue virus (BTV), the type species of the genus, indicated that RNA segments 2 and 7 of BRD virus encode the two structural core proteins, VP2 and VP7, respectively. Segment 2 is 2792 nucleotides in length with a coding capacity for a protein (VP2) of 908 amino acids and a net charge of +8.5 at neutral pH. Segment 7 is 1174 nucleotides in length with a coding capacity for a protein (VP7) of 356 amino acids and a net charge of +11.5 at neutral pH. Comparison of the two sequences with BTV serotype 10 revealed amino acid identity of 35% between the product of segment 2 and BTV VP3, and 21% between the product of segment 7 and BTV VP7. The core proteins therefore show evidence of significant evolutionary divergence compared with that shown between different insect-borne orbiviruses. In particular, the amino terminus of BRD virus VP7 differed markedly from the equivalent region in VP7 of BTV and African horse sickness virus. This region is thought to interact with the outer capsid layer of insect-borne orbiviruses.

Amino Acid Sequence↗

PubMed1999

Molecular analysis of the genome of Chuzan virus, a member of the Palyam serogroup viruses, and its phylogenetic relationships to other orbiviruses.

The nucleotide sequence of the entire genome of Chuzan virus, which belongs to the Palyam serogroup orbiviruses and causes congenital abnormalities of cattle, has been completed by analysis of the genes encoding minor core proteins (VP1, VP4 and VP6) and non-structural proteins (NS1, NS2 and NS3). The genome of Chuzan virus is 18,915 bp in length and the coding capacity of its open reading frames is 6071 aa. Comparative sequence analysis with other serogroups of the genus Orbivirus indicated that the outer capsid protein VP2, which is the neutralizing antigen, appears to be the most variable and the major core protein VP3 is the most conserved. Overall, the structural proteins, with the exception of VP2, are more conserved than the non-structural proteins among orbiviruses. Chuzan virus is phylogenetically most related to African horsesickness virus.

Base Sequence↗

PubMed1991

Phylogenetic analyses of the complete nucleotide sequence of the capsid protein (VP3) of Australian epizootic haemorrhagic disease of deer virus (serotype 2) and cognate genes from other orbiviruses.

The complete nucleotide sequence of the minor capsid protein (VP3) of epizootic haemorrhagic disease of deer virus (EHDV; Australian serotype 2) was determined using a combination of cloning and sequencing methods. Gene segment 3 that coded for the EHDV VP3 capsid protein was 2768 nucleotides in length with a coding region of 2697 nucleotides flanked by 5' and 3' non-coding regions of 17 and 53 nucleotides, respectively. A protein of 899 amino acids (Mr 103,160) having no overall charge at neutral pH was deduced from the nucleotide sequence. Comparisons with equivalent regions from the other Australian EHDV serotypes showed the VP3 genes and the segments that coded for them were similar, varying by a maximum of 5%. Comparisons with known cognate genes from bluetongue viruses showed that their VP3 genes and the proteins translated from them were remarkably similar to those of EHDV, having approximately 70% to 80% homology at either level, respectively. In an attempt to delineate the evolution of orbiviruses, we have obtained sequence data from the VP3 genes from representative members of all Australian orbiviruses now known. Computer analyses of this data enabled a phylogenetic tree for the orbiviruses to be proposed that incorporated the concept of topotypes.

Amino Acid Sequence↗

PubMed1986

Biological and antigenic characterization of Netivot virus, an unusual new Orbivirus recovered from mosquitoes in Israel.

The antigenic and biological characteristics of a new Orbivirus, designated Netivot virus, are described. This agent was originally recovered in cultures of the C6/36 clone of Aedes albopictus cells from a pool of Culex pipiens captured in Israel. Netivot virus is not pathogenic for newborn mice, nor did it initially produce detectable cytopathic effect (CPE) in Vero cells. It is closely related antigenically to Umatilla and Llano Seco viruses; these 3 agents appear to constitute a new serogroup within the genus Orbivirus. Netivot virus is also more distantly related to a number of other orbiviruses in the blue-tongue, epizootic hemorrhagic disease of deer, and Eubenangee serogroups. Netivot virus replicated to high titer and produced CPE in a variety of mosquito cell cultures, but it did not grow in 2 sand fly cell lines. Inoculation of Ae. aegypti and Ae. albopictus with Netivot virus resulted in almost 100% mortality in both species within 15 days after infection. The recovery of this and a number of other yet unidentified viral agents from field-collected mosquitoes in cultures of C6/36 cells, but not in the conventional vertebrate assay systems, suggests the existence in nature of many yet unrecognized mosquito-associated viruses. It also demonstrates the value of using new isolation methods in arbovirus studies.

Aedes↗

PubMed1985

Speciation in orbiviruses.

The definition of Orbivirus species should be based on the ability of virus populations to reassort genetic information. Application of the definition of biological species to orbiviruses enables consideration to be given the evolutionary tendencies of virus populations and to mechanisms for generating diversity within orbiviruses.

Bluetongue virus↗

PubMed1985

Problems in the interpretation of diagnostic tests due to cross-reactions between orbiviruses and broad serological responses in animals.

Tests presently used for the diagnosis of infections by bluetongue virus (BTV) or related orbiviruses are based on the use of 2 types of serological reactions. Those that are considered group-reactive tests are the agar gel diffusion precipitin (AGDP), complement-fixation (CF) and fluorescent antibody tests and those that are considered type-specific are a wide variety of virus neutralization tests (50% and 80% plaque reduction, plaque inhibition and microtiter neutralization) and cross-protection tests. These tests suffer from problems of standardization between laboratories and of specificity. Group-reactive tests (AGDP and CF) for the BTV serogroup also detect cross-reactions with viruses in the epizootic hemorrhagic disease virus (EHDV), Eubenangee (EUB) and Palyam (PAL) serogroups, with the EHDV cross-reactions being of particular concern. Further, multiple infections of cattle with PAL serogroup members can produce antibodies which will react to BTV and EHDV serogroup antigens in serological tests. Multiple infections of animals with related viruses can produce antibodies which will cross-react with orbiviruses in type-specific, virus neutralization tests to a virus which the animal has not previously been exposed. These observations stress the need to evaluate the tests at present being used, to assess the risks of cross-reactions between related orbiviruses and to develop new tests of defined specificity.

Animals↗