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At least 19 recordsLinked to original sources

Micromonas pusilla reovirus: a new member of the family Reoviridae assigned to a novel proposed genus (Mimoreovirus).

Micromonas pusilla reovirus (MpRV) is an 11-segmented, double-stranded RNA virus isolated from the marine protist Micromonas pusilla. Sequence analysis (including conserved termini and presence of core motifs of reovirus polymerase), morphology and physicochemical properties confirmed the status of MpRV as a member of the family Reoviridae. Electron microscopy showed that intact virus particles are unusually larger (90-95 nm) than the known size of particles of viruses belonging to the family Reoviridae. Particles that were purified on caesium chloride gradients had a mean size of 75 nm (a size similar to the size of intact particles of members of the family Reoviridae), indicating that they lost outer-coat components. The subcore particles had a mean size of 50 nm and a smooth surface, indicating that MpRV belongs to the non-turreted Reoviridae. The maximum amino acid identity with other reovirus proteins was 21 %, which is compatible with values existing between distinct genera. Based on morphological and sequence findings, this virus should be classified as the representative of a novel genus within the family Reoviridae, designated Mimoreovirus (from Micromonas pusilla reovirus). The topology of the phylogenetic tree built with putative polymerase sequences of the family Reoviridae suggested that the branch of MpRV could be ancestral. Further analysis showed that segment 1 of MpRV was much longer (5792 bp) than any other reovirus segment and encoded a protein of 200 kDa (VP1). This protein exhibited significant similarities to O-glycosylated proteins, including viral envelope proteins, and is likely to represent the additional outer coat of MpRV.

Amino Acid Sequence↗

Sequence determination and analysis of the full-length genome of colorado tick fever virus, the type species of genus Coltivirus (Family Reoviridae).

The Colorado tick fever virus (CTFV) is the type species of genus Coltivirus, family Reoviridae. Its genome consisting of 12 segments of dsRNA was completely sequenced. It was found to be 29,174 nucleotides long (the longest of all Reoviridae genomes characterized to date). Conserved sequences at the 5' end (SACUUUUGY) and at the 3' end (WUGCAGUS) of the 12 segments were identified. The analysis of the putative proteins deduced from the nucleotide sequences permitted to identify functional motifs. In particular, the VP1 was identified unambiguously as the viral RNA dependent RNA pylmerase (RDRP) (VP1pol), with a GDD located at a similar position to Reoviridae RDRPs. In other genes, RGD cell-binding, NTPAse, single strand binding protein and kinase motifs were identified. Comparison with Reoviridae proteins showed significant similarities to RDRPs (CTFV-VP1) and sigma C protein of orthoreovirus (CTFV-VP6). Similarities to nonviral enzymatic proteins, such as methyltransferases, NTPAses, RNA replication factors, were also identified.

Animals↗

Association of Reoviridae particles in an enteric syndrome of poults observed in turkey flocks during 1988.

An enteric syndrome of turkey poults, characterized by enteritis, crop mycosis, intestinal changes (pale, thin-walled ballooning with watery contents), and rickets, occurred during 1988 in 74 turkey flocks from different farms belonging to 9 California turkey growers. The flocks ranged in size from 9,000 to 120,000 birds. Pools of intestine sections from 618 birds, representing 78 field cases, were examined. Histopathological examination of the intestines showed a mild to severe atrophy with a reduced depth of crypts, which was more prominent in the distal part of the small intestine. Viral isolation attempts with primary cell cultures of chicken embryo kidney cells were negative. Examination by electron microscopy of negatively stained intestinal specimens revealed the presence of Reoviridae particles of 58.8 to 80 nm in diameter. Enzyme-linked immunosorbent assay results on the intestinal pools for mammalian and group A avian rotaviruses were negative. A statistically significant relationship was found for the presence of Reoviridae particles in the intestines of 10-21-day-old birds. Of the 7 most common pathological conditions analyzed, 2, rickets and intestinal changes (thin-walled ballooning intestine with watery contents), showed a statistically significant association with the presence of Reoviridae particles.

Age Factors↗

Electron microscopic and antigenic studies of uncharacterized viruses. III. Evidence suggesting the placement of viruses in the family Reoviridae.

This is the last of three papers describing the use of electron microscopy and antigenic tests intended to characterize and place in taxa more than 60 previously unclassified viruses. The first paper describes the viruses we classified as members of the families Arenaviridae, Paramyxoviridae, or Poxviridae. The second paper describes those classified as members of the virus family Bunyaviridae. Another paper, published separately, discusses viruses classified as members of the family Rhabdoviridae. In this paper we report that electron microscopy provided sufficient evidence to provisionally place 14 viruses in the family Reoviridae. By using serologic methods, we placed Minnal virus in the Umatilla serogroup and established new antigenic groups for seven other viruses (Ieri, Picola, Arkonam, Tembe, Fomede, Wongorr, and Gomoka). No antigenic relationships were determined for six other viruses (Andasibe, Itupiranga, Kammavanpettai, Lake Clarendon, Matucare, and Ndelle) provisionally placed in the family Reoviridae.

Animals↗

The Reoviridae family.

The members of the Reoviridae family are extremely varied in host ranges and have such diverse natural histories that it is compelling to conclude that their structural asset and replication strategy are uniquely successful in evolutionary terms. It follows that their study addresses fundamental aspects of virology, besides the ones which are customary with important pathogens affecting humans, animals and plants. We deal here with the present taxonomy of the family Reoviridae and of its genera, two of which (Orbivirus and Rotavirus) are treated separately in this issue. Along with a cursory presentation of the remaining genera, we give a concise update of recent findings on the genus Orthoreovirus.

Animals↗

Expansion of family Reoviridae to include nine-segmented dsRNA viruses: isolation and characterization of a new virus designated Aedes pseudoscutellaris reovirus assigned to a proposed genus (Dinovernavirus).

Family Reoviridae is known, by definition, to contain dsRNA viruses with 10-12 genome segments. We report here the characterization of the first member of this family with a nine-segmented genome. This virus was isolated from Aedes pseudoscutellaris mosquito cells and designated aedes pseudoscutellaris reovirus (APRV). Virions are single-shelled with turrets but are non-occluded by contrast to cypoviruses. APRV replicates in various mosquito cell lines, but not in mice or mammalian cells. Complete sequence analysis showed that APRV is phylogenetically related to cypoviruses, fijiviruses and oryzaviruses. The maximum amino acid identities with cypoviruses, oryzaviruses or fijiviruses in the polymerase, are compatible with values observed between these genera and lower than values within a given genus. This suggests that APRV should be classified within a new genus that we designated Dinovernavirus (sigla from D: Double-stranded, i: insect, nove: nine from the latin "novem", rna: RNA, virus) in family Reoviridae.

Aedes↗

Nucleotide sequences of double-stranded RNA segments from a hypovirulent strain of the white root rot fungus Rosellinia necatrix: possibility of the first member of the Reoviridae from fungus.

Twelve double-stranded (ds) RNA segments were detected from a hypovirulent strain W370 of the white root rot fungus Rosellinia necatrix. The estimated molecular weights ranged from 0.41 x 10(6) to 2.95 x 10(6). Full length cDNA clones for eight segments were obtained. Northern blot analysis suggested that each segment was genetically unique. The nucleotide sequences of eight full length dsRNA segments were determined. One long open reading frame was found in each segment. Conserved sequences at the 5'-end (5'-ACAAUUU-3') and at the 3'-end (5'-UGCAGAC-3') were identified in all eight segments. Segment-specific panhandle structures, formed by inverted terminal repeats, were also found in all segments. Comparative analyses of the predicted translational products of eight dsRNA segments showed that the deduced amino acid sequence partially matched those of the Reoviridae family members: Colorado tick fever virus, Nilaparvata lugens reovirus, and rice black streaked dwarf virus. The results suggested that W370 dsRNA is derived from a new member of the family Reoviridae detected in fungus.

3' Untranslated Regions↗

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↗

Genus Coltivirus (family Reoviridae): genomic and morphologic characterization of Old World and New World viruses.

We report a genomic and morphologic study of the European Eyach (EYA) virus (genus Coltivirus, family Reoviridae) and a comparative analysis with the American Colorado tick fever (CTF) virus (the type species of the genus). The previously established, but distant, antigenic relationship between these viruses was strengthened by genetic findings (presence of cognate genes, amino acid identity between 55 and 88%, similar conserved terminal motifs, suspected read-through phenomenon in segment 9 of both viruses) and by indistinguishable ultramicroscopic morphologies. Moreover, putative constitutive modifying enzyme activities were suspected to be carried out by homologous viral proteins (RNA-dependent RNA polymerase, methyl/guanylyl transferase, NTPase). These findings, together with the comparative analysis to genomes of southeast Asian isolates, support the recent classification of arboviruses with 12 segments of dsRNA within two distinct genera (genus Coltivirus and genus Seadornavirus) and raise interesting questions about the evolutionary origins of coltiviruses. The previously proposed hypothesis that EYA virus was derived from an ancestral virus introduced in Europe with the migration of lagomorphs from North-America, would imply a divergence date between American and European isolates of over 50 million years ago (MYA). This analysis allows for the first time to propose an evolutionary rate for virus dsRNA genomes which was found to be in the order of 10(-8) to 10(-9) mutations/nt/year, a rate similar to that of dsDNA genomes.

Americas↗

Sequence of genome segments 1, 2, and 3 of the grass carp reovirus (Genus Aquareovirus, family Reoviridae).

The genome segments 1, 2, and 3 of the grass carp reovirus (GCRV), a tentative species assigned to genus Aquareovirus, family Reoviridae, were sequenced. The respective segments 1, 2, and 3 were 3949, 3877, and 3702 nucleotides long. Conserved motifs 5' (GUUAUUU) and 3' (UUCAUC) were found at the ends of each segment. Each segment contains a single ORF and the negative strand does not permit identification of consistent ORFs. Sequence analysis revealed that VP2 is the viral polymerase, while VP1 might represent the viral guanylyl/methyl transferase (involved in the capping process of RNA transcripts) and VP3 the NTPase/helicase (involved in the transcription and capping of viral RNAs). The highest amino acid identities (26-41%) were found with orthoreovirus proteins. Further genomic characterization should provide insight about the genetic relationships between GCRV, aquareoviruses, and orthoreoviruses. It should also permit to precise the taxonomic status of these different viruses.

Animals↗

A member of the reoviridae (DpRV) has a ploidy-specific genomic segment in the wasp Diadromus pulchellus (Hymenoptera).

Wild and laboratory populations of the parasitoid wasp Diadromus pulchellus are infected with a new member of the reoviridae (DpRV) described in this paper. The particles of this virus possess two capsid shells (diameters: 35 and 70 nm) made up of 11 proteins. The virus is present mainly in the gut of the wasp, with smaller quantities in its venom gland. The genome of virus particles purified from haploid insects (functional males) contains 10 segments, whereas virus from diploid insects (females and sterile diploid males) contains a supernumerary 3.33-kb segment. The sequence of this dsRNA segment revealed that it is a triplicated 1050-bp motif which is 97.5% similar to the 5' region of one of the 10 basic segments, the 3.80-kb segment.

Amino Acid Sequence↗

Sequence analysis of genome segments S5 and S10 of Mal de Rio Cuarto virus (Fijivirus, Reoviridae).

Mal de Rio Cuarto virus (MRCV) was recently described as a new species of the genus Fijivirus, family Reoviridae. The nucleotide sequence of two MRCV genome segments was determined. MRCV S5 and S10 were predicted to encode proteins of 106.9 and 63.5 kDa respectively. The protein coded by MRCV S5 had 62.8% and 35.7% identity to fijiviruses RBSDV S5 and FDV S5 coded proteins, and contained a rarely reported type-1 C-terminal peroxisomal targeting signal. The protein coded by MRCV S10 had identity levels of 72.4% and 21.7% to the major outer capsid proteins of fijiviruses RBSDV S10 and NLRV S8.

Capsid Proteins↗

Nonstructural proteins involved in genome packaging and replication of rotaviruses and other members of the Reoviridae.

Rotaviruses, members of family Reoviridae, are a major cause of acute gastroenteritis of infants and young children. The rotavirus genome consists of 11 segments of double-stranded (ds)RNA and the virion is an icosahedron composed of multiple layers of protein. The virion core is formed by a layer of VP2 and contains multiple copies of the RNA-dependent RNA polymerase VP1 and the mRNA-capping enzyme VP3. Double-layered particles (DLPs), representing cores surrounded by a layer of VP6, direct the synthesis of viral mRNAs. Rotavirus core- and DLP-like replication intermediates (RIs) catalyze the synthesis of dsRNA from viral template mRNAs coincidentally with the packaging of the mRNAs into the pre-capsid structures of RIs. In addition to structural proteins, the nonstructural proteins NSP2 and NSP5 are components of RIs with replicase activity. NSP2 self assembles into octameric structures that have affinity for ssRNA and NTPase and helix-destabilizing activites. Its interaction with nucleotides induces a conformational shift in the octamer to a more condensed form. Phosphate residues generated by the NTPase activity are believed to be transferred from NSP2 to NSP5, leading to the hyperphosphorylation of the latter protein. It is suspected that the transfer of the phosphate group to NSP5 allows NSP2 to return to its noncondensed state and, thus, to accept another NTP molecule. The NSP5-mediated cycling of NSP2 from condensed to noncondensed combined with its RNA binding and helix-destabilizing activities are consistent with NSP2 functioning as a molecular motor to facilitate the packaging of template mRNAs into the pre-capsid structures of RIs. Similarities with the bluetongue virus protein NS2 and the reovirus proteins sigmaNS and micro2 suggest that they may be functional homologs of rotavirus NSP2 and NSP5.

Amino Acid Sequence↗

Viruses in the phytoreovirus genus of the Reoviridae family have the same conserved terminal sequences.

The 5'- and 3'-terminal nucleotide sequences of the dsRNA genome segments of rice dwarf virus (RDV) and rice gall dwarf virus (RGDV), members of the Phytoreovirus genus of the Reoviridae family, were determined and compared with those of wound tumour virus (WTV). The 3' tetranucleotides of the plus strand of all genome segments of RDV and RGDV were found to be the same (---UGAU 3'), except for segment 9 of RDV which had the 3'-terminal sequence---CGAU 3'. The conserved 3'-terminal sequence (---UGAU 3') was the same as that found in the genome segments of WTV, another member of the Phytoreovirus genus. On the other hand, the 5' termini of the plus strands of RDV and RGDV were found to have two or three types of common sequence. RDV had either 5' GGCAAA--- or 5' GGUAAA---, whereas RGDV had 5' GGCAUUUU---, 5' GGUAUUUU--- or 5' GGUAAUUU---. These conserved sequences were similar to the conserved 5'-terminal sequence of WTV (5' GGUAUU---). Although the three viruses differ in plant host range, tissue specificity, vector specificity and disease symptom expression, these results suggest that they have a common ancestral origin.

Base Sequence↗

Morphological and genomic characterization of two reoviruses (P and W2) pathogenic for marine crustaceans; do they constitute a novel genus of the Reoviridae family?

P and W2 viruses are pathogenic in two crustaceans of the Mediterranean Sea, Macropipus depurator and Carcinus mediterraneus, respectively. Investigation of virus, virus density and genome structure leads us to propose their classification in a genus similar to aquareovirus of the Reoviridae family. They differ from aquareoviruses by the number of dsRNA segments forming the genome (12 instead of 11), their electrophoretic pattern in PAGE (1/5/6 instead of 3/3/5), and the absence of virus replication in fish cell lines.

Animals↗

Complete sequence determination and genetic analysis of Banna virus and Kadipiro virus: proposal for assignment to a new genus (Seadornavirus) within the family Reoviridae.

Arboviruses with genomes composed of 12 segments of double-stranded (ds) RNA have previously been classified as members or probable members of the genus Coltivirus within the family REOVIRIDAE: A number of these viruses have been isolated in North America and Europe and are serologically and genetically related to Colorado tick fever virus, the Coltivirus type species. These isolates constitute subgroup A of the coltiviruses. The complete genome sequences are now presented of two Asian arboviruses, Kadipiro virus (KDV) and Banna virus (BAV), which are currently classified as subgroup B coltiviruses. Analysis of the viral protein sequences shows that all of the BAV genome segments have cognate genes in KDV. The functions of several of these proteins were also indicated by this analysis. Proteins with dsRNA-binding domains or with significant similarities to polymerases, methyltransferases, NTPases or protein kinases were identified. Comparisons of amino acid sequences of the conserved polymerase protein have shown that BAV and KDV are only very distantly related to the subgroup A coltiviruses. These data demonstrate a requirement for the subgroup B viruses to be reassigned to a separate new genus, for which the name Seadornavirus is proposed.

Animals↗

Complete genome sequence of Mycoreovirus-1/Cp9B21, a member of a novel genus within the family Reoviridae, isolated from the chestnut blight fungus Cryphonectria parasitica.

Mycoreovirus 1 (MYRV-1) is the type species of the newly described genus Mycoreovirus of the large virus family Reoviridae. The virus was isolated from a hypovirulent strain (9B21) of the chestnut blight fungus, Cryphonectria parasitica. A previous study showed that double-shelled particles introduced to fungal spheroplasts resulted in stably infected colonies. Of the 11 double-stranded RNA genomic segments (S1-S11), the three largest (S1-S3) were sequenced previously and shown to have moderate levels of similarity to the homologous segments of mammal-pathogenic coltiviruses (Eyach virus and Colorado tick fever virus) and another fungus-infecting reovirus, Mycoreovirus 3 of Rosellinia necatrix strain W370 (MYRV-3/RnW370). The sequences of the remaining segments (S4-S11) are reported here. All of the segments have single ORFs on their positive strands and the terminal sequences 5'-GAUCA----GCAGUCA-3' are conserved among currently and previously sequenced segments. Oligo-cap analysis showed that the positive strands of the genomic segments are capped, whereas the negative strands are not. Similarities among the four evolutionarily related viruses include low or moderate levels of amino acid sequence identity (14.7-34.2 %) and isoelectric points among equivalent polypeptides, e.g. proteins encoded by segments S4 and S5 of the four viruses. Phylogenetic analysis indicated that MYRV-1/Cp9B21 is related more closely to MYRV-3/RnW370 than to the coltiviruses. An interesting dissimilarity is found in codon-choice pattern among the four viruses, i.e. MYRV-1/Cp9B21 segments have a lower frequency of [XYG+XYC] than corresponding segments of the other viruses, suggesting a possible adjustment of virus codon usage to their host environments.

Amino Acid Sequence↗

Structural organization of an encephalitic human isolate of Banna virus (genus Seadornavirus, family Reoviridae).

Banna virus (BAV) is the type species of the genus Seadornavirus within the family Reoviridae. The Chinese BAV isolate (BAV-Ch), which causes encephalitis in humans, was shown to have a structural organization and particle morphology reminiscent of that of rotaviruses, with fibre proteins projecting from the surface of the particle. Intact BAV-Ch virus particles contain seven structural proteins, two of which (VP4 and VP9) form the outer coat. The inner (core) particles contain five additional proteins (VP1, VP2, VP3, VP8 and VP10) and are 'non-turreted', with a relatively smooth surface appearance. VP2 is the 'T = 2' protein that forms the innermost 'subcore' layer, whilst VP8 is the 'T = 13' protein forming the core-surface layer. Sequence comparisons indicate that BAV VP9 and VP10 are equivalent to the VP8* and VP5* domains, respectively, of rotavirus outer-coat protein VP4 (GenBank accession no. P12976). VP9 has also been shown to be responsible for virus attachment to the host-cell surface and may be involved in internalization. These similarities reveal a previously unreported genetic link between the genera Rotavirus and Seadornavirus, although the expression of BAV VP9 and VP10 from two separate genome segments, rather than by the proteolytic cleavage of a single gene product (as seen in rotavirus VP4), suggests a significant evolutionary jump between the members of these two genera.

Amino Acid Sequence↗