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At least 19 recordsLinked to original sources
PubMed2004

Reptilian reovirus: a new fusogenic orthoreovirus species.

The fusogenic subgroup of orthoreoviruses contains most of the few known examples of non-enveloped viruses capable of inducing syncytium formation. The only unclassified orthoreoviruses at the species level represent several fusogenic reptilian isolates. To clarify the relationship of reptilian reoviruses (RRV) to the existing fusogenic and nonfusogenic orthoreovirus species, we undertook a characterization of a python reovirus isolate. Biochemical, biophysical, and biological analyses confirmed the designation of this reptilian reovirus (RRV) isolate as an unclassified fusogenic orthoreovirus. Sequence analysis revealed that the RRV S1 and S3 genome segments contain a novel conserved 5'-terminal sequence not found in other orthoreovirus species. In addition, the gene arrangement and the coding potential of the bicistronic RRV S1 genome segment differ from that of established orthoreovirus species, encoding a predicted homologue of the reovirus cell attachment protein and a unique 125 residue p14 protein. The RRV S3 genome segment encodes a homologue of the reovirus sigma-class major outer capsid protein, although it is highly diverged from that of other orthoreovirus species (amino acid identities of only 16-25%). Based on sequence analysis, biological properties, and phylogenetic analysis, we propose this python reovirus be designated as the prototype strain of a fifth species of orthoreoviruses, the reptilian reoviruses.

Amino Acid Sequence↗
PubMed2004

Orthoreovirus and Aquareovirus core proteins: conserved enzymatic surfaces, but not protein-protein interfaces.

Orthoreoviruses and Aquareoviruses constitute two respective genera in the family Reoviridae of double-stranded RNA viruses. Orthoreoviruses infect mammals, birds, and reptiles and have a genome comprising 10 RNA segments. Aquareoviruses infect fish and have a genome comprising 11 RNA segments. Despite these differences, recent structural and nucleotide sequence evidence indicate that the proteins of Orthoreoviruses and Aquareoviruses share many similarities. The focus of this review is on the structure and function of the Orthoreovirus core proteins lambda1, lambda2, lambda3, and sigma2, for which X-ray crystal structures have been recently reported. The homologous core proteins in Aquareoviruses are VP3, VP1, VP2, and VP6, respectively. By mapping the locations of conserved residues onto the Orthoreovirus crystal structures, we have found that enzymatic surfaces involved in mRNA synthesis are well conserved between these two groups of viruses, whereas several surfaces involved in protein-protein interactions are not well conserved. Other evidence indicates that the Orthoreovirus mu2 and Aquareovirus VP5 proteins are homologous, suggesting that VP5 is a core protein as mu2 is known to be. These findings provide further evidence that Orthoreoviruses and Aquareoviruses have diverged from a common ancestor and contribute to a growing understanding of the functions of the core proteins in viral mRNA synthesis.

Amino Acid Sequence↗
PubMed1999

Extensive sequence divergence and phylogenetic relationships between the fusogenic and nonfusogenic orthoreoviruses: a species proposal.

The orthoreoviruses can be divided into subgroups based on either their restricted host range or the unusual ability of certain members of this group of nonenveloped viruses to induce cell-cell fusion from within. Phylogenetic relationships cannot be inferred based on these biological properties because fusogenic reoviruses are present in both the avian and mammalian subgroups. To address this issue, the complete nucleotide sequences of the three S-class genome segments encoding the major sigma-class core, outer capsid, and nonstructural proteins of four fusogenic reoviruses were determined and used to establish the phylogeny of the orthoreoviruses. The viruses analysed included two strains of avian reovirus and the only known fusogenic mammalian reoviruses, Nelson Bay virus and baboon reovirus. Comparative sequence analysis of these fusogenic reoviruses and the prototypical nonfusogenic mammalian reoviruses indicated a highly diverged genus with both conserved and unique sequence-predicted structural motifs in the major sigma-class proteins. Phylogenetic analysis provided the basis for the first taxonomic subdivision of the orthoreoviruses into species classes based on inferred evolutionary relationships. It is proposed that the orthoreoviruses consist of at least four species that separate into three clades. The nonfusogenic mammalian reovirus species represent a single clade, and the fusogenic reoviruses separate into two distinct clades. The first clade of fusogenic reoviruses contains the avian reovirus- and Nelson Bay virus-type species, with the second clade being occupied by the single baboon reovirus isolate that represents a fourth orthoreovirus species.

Amino Acid Sequence↗
PubMed2005

Structure of avian orthoreovirus virion by electron cryomicroscopy and image reconstruction.

Among members of the genus Orthoreovirus, family Reoviridae, a group of non-enveloped viruses with genomes comprising ten segments of double-stranded RNA, only the "non-fusogenic" mammalian orthoreoviruses (MRVs) have been studied to date by electron cryomicroscopy and three-dimensional image reconstruction. In addition to MRVs, this genus comprises other species that induce syncytium formation in cultured cells, a property shared with members of the related genus Aquareovirus. To augment studies of these "fusogenic" orthoreoviruses, we used electron cryomicroscopy and image reconstruction to analyze the virions of a fusogenic avian orthoreovirus (ARV). The structure of the ARV virion, determined from data at an effective resolution of 14.6 A, showed strong similarities to that of MRVs. Of particular note, the ARV virion has its pentameric lambda-class core turret protein in a closed conformation as in MRVs, not in a more open conformation as reported for aquareovirus. Similarly, the ARV virion contains 150 copies of its monomeric sigma-class core-nodule protein as in MRVs, not 120 copies as reported for aquareovirus. On the other hand, unlike that of MRVs, the ARV virion lacks "hub-and-spokes" complexes within the solvent channels at sites of local sixfold symmetry in the incomplete T=13l outer capsid. In MRVs, these complexes are formed by C-terminal sequences in the trimeric mu-class outer-capsid protein, sequences that are genetically missing from the homologous protein of ARVs. The channel structures and C-terminal sequences of the homologous outer-capsid protein are also genetically missing from aquareoviruses. Overall, the results place ARVs between MRVs and aquareoviruses with respect to the highlighted features.

Amino Acid Sequence↗
PubMed2026

Molecular Pathogenesis, Global Epidemiological Trends, and Treatment Strategies for Pteropine Orthoreoviruses: A Narrative Review.

Pteropine orthoreoviruses are emerging bat-borne zoonotic viruses of the genus Orthoreovirus (family Reoviridae), increasingly recognized as causes of acute respiratory disease in humans. Originally grouped with the largely non-pathogenic mammalian orthoreoviruses, they have challenged that view through their association with severe influenza-like illness, evidence of human-to-human transmission, and a broad geographic range across the Old World. Maintained primarily in fruit bats of the family Pteropodidae, they are now linked to neurological as well as respiratory disease. This narrative review synthesizes current knowledge of their molecular pathogenesis, zoonotic ecology, and global epidemiology, integrating recent advances in phylogeography, reassortment-driven evolution, spillover dynamics, and translational biomedical applications within a unified One Health framework. Genomic diversity, reassortment potential, and the unique fusion-associated small transmembrane proteins together underpin viral adaptability and pathogenicity. Major gaps nonetheless remain in transmission dynamics, host adaptation, shedding ecology, and pandemic potential. Future priorities should include integrated genomic surveillance, improved diagnostic strategies, validated experimental models, and interdisciplinary One Health approaches to strengthen outbreak preparedness and prevention.

Bat-borne viruses↗
PubMed2000

Outbreak of Orthoreovirus-induced meningoencephalomyelitis in baboons.

BACKGROUND AND PURPOSE: Spontaneous viral encephalitis is rare in the baboon; yet, during a 13-month period (1993-1994), eight juvenile baboons (Papio cynocephalus spp.) developed acute, progressive nonsuppurative meningoencephalomyelitis caused by an unknown agent. Clinical signs of disease included disorientation and truncal ataxia that rapidly progressed to hemiparesis or paraparesis. Clinicopathologic findings were not remarkable and appreciable gross lesions were not seen at necropsy. Microscopic examination revealed CNS lesions that were characterized by lymphoplasmacytic perivascular cuffing, microglial nodules, demyelination, axonal degeneration, vacuolization, and hemorrhage. Subsequently, a novel syncytium-inducing mammalian orthoreovirus was isolated from the brain tissue of five baboons with clinical signs of infection. METHODS: To confirm the etiologic role of the orthoreovirus, two juvenile baboons were inoculated with the virus, then were monitored for 6 weeks. RESULTS: Lesions similar to those seen in spontaneous cases were found in the CNS, and orthoreovirus was isolated from the brain of both animals. CONCLUSION: Analysis of the outbreak indicated juvenile baboons were most susceptible to disease and the virus had a possible incubation time of 46 to 66 days, but did not indicate a source of the virus or mode of transmission.

Animals↗
PubMed2001

Sequence characterization of Ndelle virus genome segments 1, 5, 7, 8, and 10: evidence for reassignment to the genus Orthoreovirus, family Reoviridae.

The full-length nucleotide sequences of genome segments 1, 5, 7, 8 and 10 from Ndelle virus (NDEV) have been characterized. Comparison of the deduced protein amino acid sequences with those of other member viruses of the family Reoviridae demonstrates that NDEV was originally assigned incorrectly to the genus Orbivirus (aa identity values of <20%). In contrast, high levels of amino acid identity were found with members of the species Mammalian orthoreovirus (MRV); for example, amino acid identity in gamma3(Pol) is between 91 and 97%. These findings, together with previous antigenic analyses, provide evidence that NDEV should be reclassified as a new serotype (designated MRV-4) within the Mammalian orthoreovirus species.

Genome, Viral↗
PubMed1998

Internal/structures containing transcriptase-related proteins in top component particles of mammalian orthoreovirus.

The structure of mammalian orthoreovirus top component particles, which are profoundly deficient in the content of double-stranded RNA genome, was determined at 30 A resolution by transmission cryoelectron microscopy and three-dimensional image reconstruction. Previously undetected, ordered densities, appearing primarily as pentameric flowers in the reconstruction, were seen to extend 65 A inwardly from the inner capsid at the icosahedral fivefold axes. Identically positioned but lower density elements were observed in two types of partially uncoated top component particles obtained by limited proteolysis. The levels of three inner-capsid proteins-lamda 1, lamda 3, and mu 2-were reduced in concert with the internal densities during proteolytic uncoating. Since lamda 3 contains the catalytic regions of the viral RNA polymerase and since both lamda 1 and mu 2 appear to play roles in transcription or mRNA capping, the internal structures are concluded to be complexes of the viral transcriptase-related enzymes. The findings have implications for the mechanisms of transcription and mRNA capping by orthoreovirus particles.

Animals↗
PubMed2005

Pulau virus; a new member of the Nelson Bay orthoreovirus species isolated from fruit bats in Malaysia.

After the outbreak of Nipah virus (NiV) in 1998-99, which resulted in 105 human deaths and the culling of more than one million pigs, a search was initiated for the natural host reservoir of NiV on Tioman Island off the east coast of Malaysia. Three different syncytia-forming viruses were isolated from fruit bats on the island. They were Nipah virus, Tioman virus (a novel paramyxovirus related to Menangle virus), and a reovirus, named Pulau virus (PuV), which is the subject of this study. PuV displayed the typical ultra structural morphology of a reovirus and was neutralised by serum against Nelson Bay reovirus (NBV), a reovirus isolated from a fruit bat (Pteropus poliocephalus) in Australia over 30 years ago. PuV was fusogenic and formed large syncytia in Vero cells. Comparison of dsRNA segments between PuV and NBV showed distinct mobility differences for the S1 and S2 segments. Complete sequence analysis of all four S segments revealed a close relationship between PuV and NBV, with nucleotide sequence identity varying from 88% for S3 segment to 56% for the S1 segment. Similarly phylogenetic analysis of deduced protein sequences confirmed that PuV is closely related to NBV. In this paper we discuss the similarities and differences between PuV and NBV which support the classification of PuV as a novel mammalian, fusogenic reovirus within the Nelson Bay orthoreovirus species, in the genus Orthoreovirus, family Reoviridae.

Animals↗
PubMed2002

Common evolutionary origin of aquareoviruses and orthoreoviruses revealed by genome characterization of Golden shiner reovirus, Grass carp reovirus, Striped bass reovirus and golden ide reovirus (genus Aquareovirus, family Reoviridae).

Full-length and partial genome sequences of four members of the genus Aquareovirus, family Reoviridae (Golden shiner reovirus, Grass carp reovirus, Striped bass reovirus and golden ide reovirus) were characterized. Based on sequence comparison, the unclassified Grass carp reovirus was shown to be a member of the species Aquareovirus C. The status of golden ide reovirus, another unclassified aquareovirus, was also examined. Sequence analysis showed that it did not belong to the species Aquareovirus A or C, but assessment of its relationship to the species Aquareovirus B, D, E and F was hampered by the absence of genetic data from these species. In agreement with previous reports of ultrastructural resemblance between aquareoviruses and orthoreoviruses, genetic analysis revealed homology in the genes of the two groups. This homology concerned eight of the 11 segments of the aquareovirus genome (amino acid identity 17-42%), and similar genetic organization was observed in two other segments. The conserved terminal sequences in the genomes of members of the two groups were also similar. These data are undoubtedly an indication of the common evolutionary origin of these viruses. This clear genetic relatedness between members of distinct genera is unique within the family Reoviridae. Such a genetic relationship is usually observed between members of a single genus. However, the current taxonomic classification of aquareoviruses and orthoreoviruses in two different genera is supported by a number of characteristics, including their distinct G+C contents, unequal numbers of genome segments, absence of an antigenic relationship, different cytopathic effects and specific econiches.

Amino Acid Sequence↗
PubMed2006

Attachment and cell entry of mammalian orthoreovirus.

Mammalian orthoreoviruses (reoviruses) serve as a tractable model system for studies of viral pathogenesis. Reoviruses infect virtually all mammals, but cause disease only in the very young. Prototype strains of the three reovirus serotypes differ in pathogenesis following infection of newborn mice. Reoviruses are nonenveloped, icosahedral particles that consist of ten segments of double-stranded RNA encapsidated within two protein shells, the inner core and outer capsid. High-resolution structures of individual components of the reovirus outer capsid and a single viral receptor have been solved and provide insight into the functions of these molecules in viral attachment, entry, and pathogenesis. Attachment of reovirus to target cells is mediated by the reovirus sigma1 protein, a filamentous trimer that projects from the outer capsid. Junctional adhesion molecule-A is a serotype-independent receptor for reovirus, and sialic acid is a coreceptor for serotype 3 strains. After binding to receptors on the cell surface, reovirus is internalized via receptor-mediated endocytosis. Internalization is followed by stepwise disassembly of the viral outer capsid in the endocytic compartment. Uncoating events, which require acidic pH and endocytic proteases, lead to removal of major outer-capsid protein sigma3, resulting in exposure of membrane-penetration mediator micro1 and a conformational change in attachment protein sigma1. After penetration of endosomes by uncoated particles, the transcriptionally active viral core is released into the cytoplasm, where replication proceeds. Despite major advances in defining reovirus attachment and entry mechanisms, many questions remain. Ongoing research is aimed at understanding serotype-dependent differences in reovirus tropism, viral cell-entry pathways, the individual and corporate roles of acidic pH and proteases in viral entry, and micro1 function in membrane penetration.

Amino Acid Sequence↗
PubMed2006

Detection and identification of avian, duck, and goose reoviruses by RT-PCR: goose and duck reoviruses are part of the same genogroup in the genus Orthoreovirus.

A reverse transcription-polymerase chain reaction (RT-PCR) procedure for the detection of avian, duck, and goose reovirus (ARV, DRV, and GRV) RNA from cell culture supernatant and clinical samples was established. Based on multiple sequence alignment, a pair of degenerate primers was selected and synthesized. The amplified, cloned, and sequenced 598-base-pair products from the sigmaA-encoding gene fragment from 16 isolates (ranging over 30 years) indicated that the primer regions were well conserved. The sensitivity of this method was determined to be 10(-2) PFU. The specificity of the RT-PCR method was determined by testing specimens containing avian influenza A viruses, Newcastle disease virus, and infectious bronchitis virus, all of which yielded negative results with no discernible background. The efficiency of the system for detection of ARV, DRV, and GRV directly in 71/83 clinical samples was confirmed. The nucleotide sequence analysis indicated that DRV and GRV isolated from China in different locales and years were closely related, showing 97.4-100% homology to each other, but with only 86.7-88.5% identity to DRV 89026. The nucleotide and amino acid sequence identities in the amplified sigmaA-encoding gene were 74.2-78.4% and 86.9-92.0%, respectively, between duck/goose and chicken species. Phylogenetic analysis indicated that GRV and DRV aggregated into the same specified genogroup within subgroup II of the genus Orthoreovirus and are more closely related to ARV than to Nelson Bay virus. Overall, this study developed a sensitive and specific technique for the identification ARV, DRV, and GRV, and sequencing analysis has enhanced our understanding of the evolutionary relationship between ARV, DRV, and GRV.

Animals↗
PubMed2005

Virological and molecular characterization of a mammalian orthoreovirus type 3 strain isolated from a dog in Italy.

A mammalian orthoreovirus (MRV) strain was isolated from a pup with fatal diarrhea, which had a concurrent infection by canine parvovirus type 2. The reovirus isolate showed an atypical hemagglutination pattern and a retarded electrophoretic mobility of the S1 segment, which is characteristic of MRV type 3 (MRV-3). Assignment of the isolated virus to MRV-3 was confirmed by type-specific RT-PCR assays, targeting the S1 gene, and by subsequent sequence analysis of the PCR product. By phylogeny based on the S1 gene of several MRVs, the isolate fell into lineage E, along with the murine strain T3C9/61 and the bovine strains T3C18/61 and T3C31/59. Conversely, L1 sequences were found to segregate regardless of the viral type. A total of 110 fecal samples, 56 nasal and 31 ocular swabs from dogs with diarrhea or nasal/ocular discharge were tested by a nested-PCR assay specific for reoviruses, and no sample was found to contain MRV RNA, a finding that is apparently in contrast with the seroprevalence (25.77%) observed in dogs.

Animals↗
PubMed2003

Evaluation of virucidal activity of three commercial disinfectants and formic acid using bovine enterovirus type 1 (ECBO virus), mammalian orthoreovirus type 1 and bovine adenovirus type 1.

A modified version of the test method of the Comité Européen de Normalisation (CEN) was developed using formic acid and three commercial disinfectants to evaluate virucidal activity against three non-enveloped viruses, bovine enterovirus type 1 (ECBO virus), mammalian orthoreovirus type 1 and bovine adenovirus type 1 (BAV 1). Determination of the effects of temperature was carried out at 20 and 10 degrees C. All tests with protein load used bovine serum albumin (BSA) and yeast extract. The investigations were performed in suspension tests and in carrier tests using poplar wood virus carriers. The carrier tests showed that ECBO virus could be inactivated at 20 degrees C with 1% formic acid within a 60 min reaction time. For disinfection of ECBO virus at 10 degrees C within 60 min, a 2% concentration of formic acid was necessary. Formic acid was ineffective against reovirus and bovine adenovirus and cannot be recommended as a reference disinfectant. Inactivation of ECBO virus and adenovirus type 1 using a disinfectant containing aldehydes and alcohols could be achieved, but only at room temperature. The disinfection of reovirus type 1 at room temperature with this product was possible without a protein load. This disinfectant exhibited disinfection ability at 10 degrees C at a concentration of more than 2% or with a longer exposure time. A disinfectant containing aldehydes was effective at room temperature but its effect was reduced in the presence of organic matter. Inactivation at 10 degrees C was found only against adenovirus. The fourth disinfectant, which contained peroxiacetic acid, inactivated all test viruses at a concentration of 0.5% within 15 min independent of temperature and protein load.

Animals↗
PubMed2003

Nucleoside and RNA triphosphatase activities of orthoreovirus transcriptase cofactor mu2.

The mammalian Orthoreovirus (mORV) core particle is an icosahedral multienzyme complex for viral mRNA synthesis and provides a delimited system for mechanistic studies of that process. Previous genetic results have identified the mORV mu2 protein as a determinant of viral strain differences in the transcriptase and nucleoside triphosphatase activities of cores. New results in this report provided biochemical and genetic evidence that purified mu2 is itself a divalent cation-dependent nucleoside triphosphatase that can remove the 5' gamma-phosphate from RNA as well. Alanine substitutions in a putative nucleotide binding region of mu2 abrogated both functions but did not affect the purification profile of the protein or its known associations with microtubules and mORV microNS protein in vivo. In vitro microtubule binding by purified mu2 was also demonstrated and not affected by the mutations. Purified mu2 was further demonstrated to interact in vitro with the mORV RNA-dependent RNA polymerase, lambda3, and the presence of lambda3 mildly stimulated the triphosphatase activities of mu2. These findings confirm that mu2 is an enzymatic component of the mORV core and may contribute several possible functions to viral mRNA synthesis.

Acid Anhydride Hydrolases↗
PubMed1992

Further characterization of the ts453 mutant of mammalian orthoreovirus serotype 3 and nucleotide sequence of the mutated S4 gene.

The sigma 3 protein of mammalian orthoreoviruses has multiple proven and postulated roles during viral multiplication. In this manuscript we took advantage of the availability of the ts453 thermosensitive mutant, already assigned to the S4 gene encoding sigma 3, to begin the elucidation of the relationship between the two main domains and the different roles of the sigma 3 viral protein. The alteration in the mutant appeared to affect the structural role of the protein. Nucleotide sequence determination indicated an especially significant change close to the zinc finger of the protein. These data suggest that the zinc-binding region might be especially important during the assembly of sigma 3 into the viral capsid.

Base Sequence↗
PubMedDate not supplied

Studies on orthoreoviruses isolated from young turkeys. I. Isolation and characterization.

Four virus isolates were recovered from the intestinal tracts of turkey poults with diarrhea, abnormal feathering, stunted growth, and increased mortality. The isolates were clone-purified and characterized according to cytopathic effect (CPE) in chicken embryo kidney cells, size, morphology, physicochemical properties, and replicative cycle. The isolates were identified as members of the family Reoviridae, genus Orthoreovirus.

Animals↗