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PubMed1992

Strain-specific selection of genome segments in avian reovirus coinfections.

To determine whether selection of genome segments in coinfections is strain-specific, chicken embryo fibroblasts were coinfected with avian reovirus strain 883 and one of three other avian reovirus strains (176, S1133 and 81-5). Viral progeny from each coinfection (883 x 176, 883 x S1133 or 883 x 81-5) was serially passaged at a low m.o.i. The electropherotypes of the coinfection progeny and those of the plaque-derived clones obtained from passages 1 and 20 were analysed. Two 883 segments (M2 and S2) were found to be selected in the 883 x 176 coinfection, three 883 segments (M2, M3 and S2) in the 883 x S1133 coinfection, and only one 883 segment (M3) in the 883 x 81-5 coinfection, i.e. different 883 genome segments were selected in the three coinfections. It was, therefore, concluded that selection of genome segments in a coinfection of a given cell line is virus strain-specific. The selection of genome segments in coinfections was shown to be due to enhanced infectivity of the reassortants that were formed in the coinfections. In addition, defective interfering particles that lack the S1 segment were identified in the 883 x 81-5 coinfection progeny following serial passage. Selection of genome segment(s) in coinfections as described herein may have potential importance on the effect and production of divalent or multivalent vaccines.

Animals↗

PubMed1990

Nucleotide sequence analysis of genome segment A of infectious bursal disease virus.

The nucleotide sequence of genome segment A cDNA of the STC strain of infectious bursal disease virus (IBDV) was determined and compared with sequences of the homologous genome segment of the 002-73 strain of IBDV and the Jasper strain of infectious pancreatic necrosis virus (IPNV). The STC-IBDV genome segment A was determined to be 3262 base pairs (bp), which is close to the estimated total length of 3300 bp for genome segment A in IBDV, although there is no proof that it is the real length of this genome segment. The STC-IBDV genome segment A contains two major overlapping open reading frames (ORFs). The large ORF of 3036 bp predicts a polyprotein of Mr 109,358, whereas the small ORF is 435 bp and predicts a protein of Mr 16,550 in STC-IBDV. STC-IBDV and 002-73-IBDV polyproteins are closely related (97.4% amino acid homology). Most of the amino acid mismatches are in VP2 sequences, mainly within the area of the conformation-dependent epitope. Comparison with the Jasper-IPNV polyprotein reveals levels of amino acid sequence homology of about 40% in VP2, 32% in VP3 and 21% in VP4. Within the VP2 molecule the conformation-dependent epitope area is again the least homologous, but the heterogeneity is more conspicuous than between the two IBDV strains, which is not surprising since IBDV and IPNV are serologically unrelated. The small ORF proteins have about 88% amino acid sequence homology between STC-IBDV and 002-73-IBDV, and 30% between each IBDV strain and Jasper-IPNV. There is no homology at all in the non-coding regions of IBDV and IPNV. These comparative sequence data will be useful for subgrouping the Birnaviridae family.

Amino Acid Sequence↗

PubMed1989

The sequences of the reovirus serotype 1, 2, and 3 L1 genome segments and analysis of the mode of divergence of the reovirus serotypes.

We report the sequence of the L1 genome segment of reovirus serotype 3 strain Dearing, which encodes the minor core component protein lambda 3. It is 3854 bp long, with a long open reading frame starting at position 19 that is 1267 codons long. Protein lambda 3 is not detectably related to any other protein, nor does it appear to possess motifs indicative of recognized specialized functions. We have also sequenced the L1 genome segments of reovirus serotypes 1 and 2. The serotype 1 and 3 L1 genome segments are extremely closely related; there are only 154 mismatches (4.1%), 80% of which are in third base codon positions, so that these two lambda 3 proteins are 98.3% related (only 22 mismatches out of 1267). The serotype 2 L1 genome segment is only 75% related to the serotype 1 and 3 genome segments, and the serotype 2 lambda 3 protein is 92% related to the serotype 1 and 3 lambda 3 proteins. We have also analyzed the divergence patterns by which the various reovirus genome segments evolved into the three serotype forms. It appears that serotype 2 separated from the serotype 1/3 precursor long before serotypes 1 and 3 themselves diverged. In all cases the third base codon positions in the various genome segments have diverged about 80% toward randomness. The first and second base codon positions have diverged much less and to varying degree, depending, presumably, on each protein's ability to accept changes without significant loss of function. For the separation into the serotype 1 and 3 forms, the extent of divergence of the various genome varies over a very wide range. The S1 genome segments have again diverged most extensively, the extent of divergence in the first, second, and third base codon positions being about 50, 35 and 75%, respectively. For seven other genome segments that we examined the extent of third base codon position divergence is 56, 53, 48, 29, 22, 13, and 6%, whereas first and second base codon position divergence ranges from no more than 6 to 2 and 3 to less than 1%, respectively. The most likely explanation of these patterns is that the separation of the various genome segments into the present-day serotype 1 and 3 associated forms occurred at different times during evolution, from progenitors that were genome segment reassortants with survival rates as high as or higher than those of homologous genome segment sets.

Amino Acid Sequence↗

PubMed2000

Cloning of human picobirnavirus genomic segments and development of an RT-PCR detection assay.

Nearly full-length genomic segments 2 and a partial-length genomic segment 1 of human picobirnavirus were cloned and sequenced. The clones were derived from viruses obtained from human immunodeficiency virus (HIV)-infected patients in Atlanta, Georgia (strains 3-GA-91 and 4-GA-91) and a nonHIV-infected person from China (strain 1-CHN-97). The picobirnavirus genomic segments lacked sequence similarities with other viral sequences in GenBank and EMBL. Comparison of genomic segment 1 from a human and a rabbit picobirnavirus identified a region of 127 nucleotides with 54.7% identity. The genomic segments 2 of the 4-GA-91 and 1-CHN-97 strains had 41.4% nucleic acid identity and 30.0% amino acid similarity and contained amino acid motifs typical of RNA-dependent RNA polymerase genes. Reverse transcription-PCR detection assays were developed with primers targeted to the genomic segments 2 of strains 4-GA-91 or 1-CHN-97. Picobirnaviruses related to the China strain were the predominant viruses detected in stool samples from people in four countries on three continents. Picobirnaviruses were detected in samples from two outbreaks of gastroenteritis in long-term elder care facilities but were not determined to be the primary pathogen. Our findings support the view that picobirnaviruses constitute a distinct family of viruses.

Amino Acid Sequence↗

PubMed1990

Nucleotide sequence of rice dwarf virus genome segment 4.

The complete nucleotide sequence of rice dwarf virus (RDV) genome segment 4 was determined. Genome segment 4 was 2468 nucleotides long and had a long open reading frame initiating at nucleotides 64 to 66 and terminating at 2245 to 2247. The deduced polypeptide contained 727 amino acid residues with an Mr of 79.8K. Amino acid sequences similar to a 'zinc-finger' and purine NTP-binding motifs were present in the deduced polypeptide. Considerable amino acid sequence homology was detected between genome segment 4 of RDV and wound tumor virus (WTV). One of the sequences similar to the 'zinc-finger' motif was present in a conserved region of the polypeptide of both viruses. However, the sequence similar to the purine NTP-binding motif was not present in the polypeptide encoded by genome segment 4 of WTV.

Amino Acid Sequence↗

PubMed2005

The sequence and phylogenetic analysis of avian reovirus genome segments M1, M2, and M3 encoding the minor core protein muA, the major outer capsid protein muB, and the nonstructural protein muNS.

The sequences and phylogenetic analyses of the M-class genome segments of 12 avian reovirus strains are described. The S1133 M1 genome segment is 2283 base pairs long, encoding a protein muA consisted of 732 amino acids. Each M2 or M3 genome segment of 12 avian reovirus strains is 2158 or 1996 base pairs long, respectively, encoding a protein muB or muNS consisted of 676 and 635 amino acids, respectively. The S1133 genome segment has the 5' GCUUUU terminal motif, but each M2 and M3 genome segment displays the 5' GCUUUUU terminal motif which is common to other known avian reovirus genome segments. The UCAUC 3'-terminal sequences of the M-class genome segments are shared by both avian and mammalian reoviruses. Noncoding regions of both 5'- and 3'-termini of the S1133 M1 genome segment consist of 12 and 72 nucleotides, respectively, those of each M2 genome segment consist of 29 and 98 nucleotides, respectively, and those of each M3 genome segment are 24 and 64 nucleotides, respectively. Analysis of the average degree of the M-class gene and the deduced mu-class protein sequence identities indicated that the M2 genes and the muB proteins have the greatest level of sequence divergence. Computer searches revealed that the muA possesses a sequence motif (NH(2)-Leu-Ala-Leu-Asp-Pro-Pro-Phe-COOH) (residues 458-464) indicative of N-6 adenine-specific DNA methylase. Examination of the muB amino acid sequences indicated that the cleavage site of muB into muBN and muBC is between positions 42 and 43 near the N-terminus of the protein, and this site is conserved for each protein. During in vitro treatment of virions with trypsin to yield infectious subviral particles, both the N-terminal fragment delta and the C-terminal fragment phi were shown to be generated. The site of trypsin cleavage was identified in the deduced amino acid sequence of muB by determining the amino-terminal sequences of phi proteins: between arginine 582 and glycine 583. The predicted length of delta generated from muBC is very similar to that of delta generated from mammalian reovirus mu1C. Taken together, protein muB is structurally, and probably functionally, similar to its mammalian homolog, mu1. In addition, two regions near the C-terminal and with a propensity to form alpha-helical coiled-coil structures as previously indicated are observed for each protein muB. Phylogenetic analysis of the M-class genes revealed that the predicted phylograms delineated 3 M1, 5 M2, and 2 M3 lineages, no correlation with serotype or pathotype of the viruses. The results also showed that M2 lineages I-V consist of a mixture of viruses from the M1 and M3 genes of lineages I-III, reflecting frequent reassortment of these genes among virus strains.

Amino Acid Sequence↗

PubMed1993

Polydnavirus genome segment families in the ichneumonid parasitoid Hyposoter fugitivus.

Sequences homologous to encapsidated polydnavirus genome segments are routinely detected in parasitoid chromosomal DNA; typically, each viral genome segment hybridizes to a single cognate chromosomal locus. In the present study, we show that in some cases, two or more viral genome segments may hybridize to the same chromosomal locus. Genome segments of this type invariably share a majority of restriction enzyme sites, a fact suggesting derivation from a common template. Families of viral genome segments appear to be relatively common in the Hyposoter fugitivus polydnavirus genome.

Animals↗

PubMed1991

Cloning of the maize rough dwarf virus genome: molecular confirmation of the plant-reovirus classification scheme and identification of two large nonoverlapping coding domains within a single genomic segment.

The segmented double-stranded RNA genome of maize rough dwarf virus, a plant-infecting reovirus of the genus Fijivirus, was cloned and partially characterized. Nucleotide sequence analysis of full-length cDNA clones corresponding to genomic segments S6, S7, and S8 revealed each segment to contain the conserved terminal oligonucleotide sequences (+) 5' AAGUUUUUU------UGUC 3' and adjacent, segment-specific, regions of inverted complementarity (inverted repeats), a structural motif previously reported for members of the genus Phytoreovirus. Genomic segment S6 was completely sequenced and found to consist of 2193 base pairs. Computer analysis indicated that the coding strand contained two large nonoverlapping open reading frames consisting of 363 and 310 codons and located in the 5'- and 3'-terminal domains, respectively. This was confirmed by cell-free translation studies with synthetic transcripts and denatured genomic RNA. However, only the product of the 5'-proximal open reading frame, a 40-kDa polypeptide, was efficiently expressed in vitro from the full-length S6 coding strand. This represents the first case in which a reovirus genomic segment was found to contain two large open reading frames in a nonoverlapping configuration, suggesting possible alternative strategies for regulation of gene expression by members of this genus. The combined results provide a molecular confirmation of the current classification scheme for plant-infecting reoviruses. Furthermore, the fact that the same terminal structural motif is conserved across genera provides additional evidence that these elements serve an important functional role during genome transcription or replication.

Amino Acid Sequence↗

PubMed2007

Characterization of M-class genome segments of muscovy duck reovirus S14.

This report documents the first sequence analysis of the entire M1, M2, and M3 genome segments of the muscovy duck reovirus (DRV) S14. The complete sequence of each of the three M gene segments was determined. The M1 genome segment was 2283 nucleotides in length and was predicted to encode muA protein of 732 residues. The Escherichia coli expressed M1 transcripts generated a 108kDa protein, as expected for muA. A cleavage product of muA, muA1, could be detected by Western blotting with duck anti-reovirus and mouse anti-muA polyclonal serum. muA was distributed diffusely in the cytoplasma and nucleus of transfected Vero cells, which provides evidence that muA might be functional related to the mammalian reovirus (MRV) mu2. The M2 gene was 2155 nucleotides in length and was predicted to encode muB major outer capsid protein of 676 amino acids. The M3 genome segment was 1996 nucleotides in length and was predicted to encode a muNS protein of 635 amino acids. It was unexpectedly found that 5'-termini of the M1 and M2 genes ended with 5'-ACUUUU and 5'-UCUUUU, respectively, instead of 5'-GCUUUU, which is present on most mRNAs of other avian reoviruses (ARV). The UCAUC 3'-terminal sequences of the S14 M1, M2, and M3 genome segments are shared by DRV, ARV, and MRV. Alignment of the DRV muA-, muB-, and muNS-encoding genes with ARV revealed 72.9-73.9%, 67.1-69.6%, and 69.4-70.8% nucleotide identity, respectively. The amino acid sequence homology between DRV and ARV ranged from 85.3 to 86.2% (muA), 75.0 to 76.5% (muB), and 78.4 to 79.8% (muNS). Phylogenetic analyses of the M1, M2, M3, and S-class [Kuntz-Simon, G., Le Gall-Recule, G., de Boisseson, C., Jestin, V., 2002. Muscovy duck reovirus sigmaC protein is a typically encoded by the smallest genome segment. J. Gen. Virol. 83, 1189-1200; Zhang, Y., Liu, M., Hu, Q.L., Ouyang, S.D., Tong, G.Z., 2006a. Characterization of the sigmaC-encoding gene from muscovy duck reovirus. Virus Genes 36, 169-174; Zhang, Y., Liu, M., Ouyan, S.D., Hu, Q.L., Guo, D.C., Han, Z., 2006b. Detection and identification of avian, duck, and goose reoviruses by RT-PCR: goose and duck reoviruses aggregated the same specified genogroup in Orthoreovirus Genus II. Arch. Virol. 151, 1525-1538] genome segments suggests that DRV and ARV share a recent common ancestor and that the two lineages have subsequently undergone host dependent evolution.

Amino Acid Sequence↗

PubMed1989

Recombinant cDNA probe from bluetongue virus genome segment 10 for identification of bluetongue virus.

Genome segment 10 of bluetongue virus (BTV) serotype 11 UC8 strain was cloned and subsequently hybridized to viral double-stranded RNA extracted from 90 field isolates of BTV serotypes 10, 11, 13, and 17; the prototype strains of BTV 2, 10, 11, 13, and 17; the prototype strain epizootic hemorrhagic disease virus (EHDV) serotype 1; and 4 field isolates of EHDV serotype 2. The 90 field isolates were obtained from different counties in California, Louisiana, and Idaho during the years 1979, 1980, and 1981. The cloned genetic probe hybridized with all the BTV samples tested, showing different degrees of cross-hybridization at the stringency conditions used in this study. This indicated that BTV genome segment 10 has conserved nucleotide sequences among the BTV serotypes 2, 10, 11, 13, and 17. No cross-hybridization signals were detected between the cloned genome segment 10 of BTV 11 UC8 strain and the prototype strain of EHDV serotype 1 and the field isolates of serotype 2. This probe recognized a wide variety of BTV isolates.

Animals↗

PubMed1995

Acquisition of a fourth genomic segment in bacteriophage phi 6, a bacteriophage with a genome of three segments of dsRNA.

Bacteriophage phi 6 has a genome of three segments of double-stranded RNA enclosed in a polyhedral procapsid. Packaging of individual segments is dependent upon unique packaging sequences near the 5' ends of the segments. We have prepared deletions in segments L and M that decrease their size by half. Phages with these deletions can be propagated on host strains carrying plasmids with complementing genes. The deletion segments are present in two copies per virion. Phage carrying a deletion segment can acquire the transcript of the complementing plasmid if the latter has a packaging sequence. If the packaging sequence is homologous to that of the deletion segment, acquisition occurs at high frequency. If it is heterologous, then recombination exchanges the heterologous packaging sequence for a homologous one or it attaches the transcript to one of the other genomic segments.

Bacteriophages↗

PubMed1985

Analysis of the terminal sequences of the genome segments of four orbiviruses.

The RNA sequences of the terminal regions of the genome segments of 4 different orbiviruses were analysed. In 3 of these [bluetongue virus (BTV) types 1 and 20 and Ibaraki virus, a member of the epizootic hemorrhagic disease (EHD) serogroup], 1 strand of all of the genome segments analysed ends in 3'CAAUUU...5' while the other strand ends in 3'CAUUCA...5'. These conserved sequences are identical to those reported for BTV types 10 and 11. The 3' terminal sequences of segments 3 and 10 of the BTV 1 genome (including the conserved regions) were confirmed by the detection of exactly complementary sequences at the 5' termini of the ssRNA strands of opposite polarity. This also confirmed for these dsRNA segments (and by analogy for all of the genome segments of these viruses) that the dsRNA molecules are fully base-paired end to end. Using in vitro synthesised mRNA of BTV 1 in annealing experiments with the separated ssRNAs from the individual genome segments, it was shown that in each case the strand ending in 3'CAUUCA...5' is of the same polarity as the mRNA (+ve), while the strand ending in 3'CAAUUU...5' is of the opposite (-ve) polarity. The 4th virus analysed (Tilligerry, a member of the Eubenangee serogroup) only had 5 conserved bases at the 3' termini of 1 strand of each genome segment (3'CAU-CA...5') and 3 conserved bases at the 3' termini of the other strand (3'CA--U...5'). Considerable sequence homology was found in the near-terminal nonconserved regions of comparable genome segments, particularly between the different BTV types. There was little evidence however for absolute conservation of "segment specific" sequences in these regions of the RNA, as reported for rotaviruses. The percentage of sequence homology found in the terminal regions of the genome segments between members of the BTV, EHD and Eubenangee serogroups examined correlates with the serological interrelationships between these groups of viruses. The conserved terminal sequences and sequence homology in these regions of the RNA are discussed as to their role in virus replication and their significance to the reassortment of genome segments between different viruses during dual infections.

Base Sequence↗

PubMed1993

Identification of a precursor genomic segment that provided a sequence unique to glycophorin B and E genes.

Human glycophorin A, B, and E (GPA, GPB, and GPE) genes belong to a gene family located at the long arm of chromosome 4. These three genes are homologous from the 5'-flanking sequence to the Alu sequence, which is 1 kb downstream from the exon encoding the transmembrane domain. Analysis of the Alu sequence and flanking direct repeat sequences suggested that the GPA gene most closely resembles the ancestral gene, whereas the GPB and GPE genes arose by homologous recombination within the Alu sequence, acquiring 3' sequences from an unrelated precursor genomic segment. Here we describe the identification of this putative precursor genomic segment. A human genomic library was screened by using the sequence of the 3' region of the GPB gene as a probe. The genomic clones isolated were found to contain an Alu sequence that appeared to be involved in the recombination. Downstream from the Alu sequence, the nucleotide sequence of the precursor genomic segment is almost identical to that of the GPB or GPE gene. In contrast, the upstream sequence of the genomic segment differs entirely from that of the GPA, GPB, and GPE genes. Conservation of the direct repeats flanking the Alu sequence of the genomic segment strongly suggests that the sequence of this genomic segment has been maintained during evolution. This identified genomic segment was found to reside downstream from the GPA gene by both gene mapping and in situ chromosomal localization. The precursor genomic segment was also identified in the orangutan genome, which is known to lack GPB and GPE genes. These results indicate that one of the duplicated ancestral glycophorin genes acquired a unique 3' sequence by unequal crossing-over through its Alu sequence and the further downstream Alu sequence present in the duplicated gene. Further duplication and divergence of this gene yielded the GPB and GPE genes.

Base Sequence↗

PubMed1985

Assignment of simian rotavirus SA11 temperature-sensitive mutant groups B and E to genome segments.

Recombinant (reassortant) viruses were selected from crosses between temperature-sensitive (ts) mutants of simian rotavirus SA11 and wild-type human rotavirus Wa. The double-stranded genome RNAs of the reassortants were examined by electrophoresis in Tris-glycine-buffered polyacrylamide gels and by dot hybridization with a cloned DNA probe for genome segment 2. Analysis of replacements of genome segments in the reassortants allowed construction of a map correlating genome segments providing functions interchangeable between SA11 and Wa. The reassortants revealed a functional correspondence in order of increasing electrophoretic mobility of genome segments. Analysis of the parental origin of genome segments in ts+ SA11/Wa reassortants derived from the crosses SA11 tsB(339) X Wa and SA11 tsE(1400) X Wa revealed that the group B lesion of tsB(339) was located on genome segment 3 and the group E lesion of tsE(1400) was on segment 8.

Animals↗

PubMed1997

Characterization of the double-stranded RNA genome segment S3 of avian reovirus.

The double-stranded RNA genome segment S3 of avian reovirus (ARV) S1133 was cloned following polyadenylation of both strands and cDNA synthesis of S3 RNA. The complete segment S3 nucleotide sequence was determined. S3 is 1196 base pairs long with one long open reading frame (ORF). The ORF possesses the AUG initiation codon in an optimum context for translation and starts at the first initiation codon (residue 24) and extends for 367 codons, sufficient to encode a protein of the same size as the known S3 gene product, protein sigmaB, one of the major outer capsid proteins of avian reovirus (Mr 41471). Protein sigmaB was subsequently expressed in Escherichia coli. The expressed protein sigmaB was indistinguishable from virion protein sigmaB as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot assay, and N-terminal amino acid sequencing of several peptides generated by Staphyloccus aureus V8 protease digestion. ARV S3 genome segment possesses a pentanucleotide UCAUC at the 3'-terminus of its plus strand. The pentanucleotide sequence is common to the other genome segment S1 of ARV and to ten genome segments of mammalian reovirus at the 3'-terminus of their plus strands. Amino acid sequence analysis revealed that ARV sigmaB does not contain a repeated basic amino acid motif as do the three serotypes of mammalian reovirus. The results of amino acid sequencing suggest that the most susceptible cleavage sites of sigmaB to V8 protease are located in a hydrophilic area between amino acids 95 and 140.

Animals↗

PubMed1985

Diagnosis of rotavirus infection with cloned cDNA copies of viral genome segments.

The diagnostic potential of cloned cDNA copies of human rotavirus (strain WA) genome segments for the detection of rotavirus in clinical specimens has been determined. A hybridization assay in which a mixture of 32P-labeled cDNAs representing the 11 rotavirus segments was used as a probe compared favorably with three frequently used diagnostic tests for rotavirus in terms of both specificity and sensitivity. Significantly, clinical isolates could be readily distinguished when cloned cDNA copies of individual genome segments were used independently as a probe. In assays in which genome RNA from rotaviruses of known subgroups and serotypes were tested, cloned probes that encode nonstructural viral proteins hybridized efficiently to genome RNAs of all strains, whereas cloned probes corresponding to genome segments 6 and 9 exhibited the potential for differentiating strains of different subgroups and serotypes. Cloned cDNA copies of rotavirus genome segments therefore offer considerable potential for improved general diagnosis of rotavirus in clinical specimens, as well as for epidemiological studies in which virus isolates can be distinguished on the basis of nucleotide sequence homology of individual genome segments.

Cloning, Molecular↗

PubMed2004

Comparisons of the M1 genome segments and encoded mu2 proteins of different reovirus isolates.

BACKGROUND: The reovirus M1 genome segment encodes the mu2 protein, a structurally minor component of the viral core, which has been identified as a transcriptase cofactor, nucleoside and RNA triphosphatase, and microtubule-binding protein. The mu2 protein is the most poorly understood of the reovirus structural proteins. Genome segment sequences have been reported for 9 of the 10 genome segments for the 3 prototypic reoviruses type 1 Lang (T1L), type 2 Jones (T2J), and type 3 Dearing (T3D), but the M1 genome segment sequences for only T1L and T3D have been previously reported. For this study, we determined the M1 nucleotide and deduced mu2 amino acid sequences for T2J, nine other reovirus field isolates, and various T3D plaque-isolated clones from different laboratories. RESULTS: Determination of the T2J M1 sequence completes the analysis of all ten genome segments of that prototype. The T2J M1 sequence contained a 1 base pair deletion in the 3' non-translated region, compared to the T1L and T3D M1 sequences. The T2J M1 gene showed approximately 80% nucleotide homology, and the encoded mu 2 protein showed approximately 71% amino acid identity, with the T1L and T3D M1 and mu2 sequences, respectively, making the T2J M1 gene and mu2 proteins amongst the most divergent of all reovirus genes and proteins. Comparisons of these newly determined M1 and mu2 sequences with newly determined M1 and mu2 sequences from nine additional field isolates and a variety of laboratory T3D clones identified conserved features and/or regions that provide clues about mu2 structure and function. CONCLUSIONS: The findings suggest a model for the domain organization of mu2 and provide further evidence for a role of mu2 in viral RNA synthesis. The new sequences were also used to explore the basis for M1/mu2-determined differences in the morphology of viral factories in infected cells. The findings confirm the key role of Ser/Pro208 as a prevalent determinant of differences in factory morphology among reovirus isolates and trace the divergence of this residue and its associated phenotype among the different laboratory-specific clones of type 3 Dearing.

Animals↗

PubMed2000

Characterization of phi 13, a bacteriophage related to phi 6 and containing three dsRNA genomic segments.

The three dsRNA genomic segments of bacteriophage Phi 13 were copied as cDNA and the nucleotide sequences were determined. The organization of the genome is similar to that of Phi 6, and there is significant similarity in the amino acid sequences of the proteins of the polymerase complex and one of the membrane proteins, P6. There is little or no similarity in the nucleotide sequences. Several features of the viral proteins differ markedly from those of Phi 6. Although both phages are covered by a lipid-containing membrane, the protein compositions are different. The host attachment protein consists of two peptides rather than one and the phage attaches directly to the LPS of the host rather than to a Type IV pilus. Despite the differences in the structure of the membranes, the two viruses can successfully exchange the genes for host attachment proteins and thereby change their host specificities.

Bacteriophage phi 6↗