51
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Onodera S, Qiao X, Qiao J, Mindich L. Directed changes in the number of double-stranded RNA genomic segments in bacteriophage phi6. Proc Natl Acad Sci U S A 1998; 95:3920-4. [PMID: 9520468 PMCID: PMC19938 DOI: 10.1073/pnas.95.7.3920] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/1997] [Indexed: 02/06/2023] Open
Abstract
Bacteriophage Phi6 has a genome of three segments of double-stranded RNA. The segments are designated S, M, and L. Each segment has a unique packaging site, pac, near the 5' end of the plus strand. The plus strands of the segments are normally packaged in the order S, M, L. Chimeras of segment M and S in which segment M is at the 5' end of the plus strand can be stably incorporated into the virion; however, an independent segment S must be included along with normal segment L, even if it contains no active genes. A chimera of segment M and S in which segment S is at the 5' end of the plus strand can be stably incorporated into the virion along with normal segment L to form a two-segment genome. A chimera of segments S, M, and L in which the packaging sequence is that of S can also form a stable nonsegmented genome. These findings are consistent with a model that we have proposed for the packaging of the Phi6 genome.
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Affiliation(s)
- S Onodera
- Department of Microbiology, The Public Health Research Institute, New York, NY 10016, USA
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52
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Qiao X, Qiao J, Mindich L. Stoichiometric packaging of the three genomic segments of double-stranded RNA bacteriophage phi6. Proc Natl Acad Sci U S A 1997; 94:4074-9. [PMID: 9108107 PMCID: PMC20570 DOI: 10.1073/pnas.94.8.4074] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/1997] [Accepted: 02/14/1997] [Indexed: 02/04/2023] Open
Abstract
A model that explains the stoichiometric packaging of the chromosomes of phi6, a bacteriophage with a genome of three unique double-stranded RNA segments, is proposed and supported. Ordered switches in packaging specificity and RNA synthesis are determined by the amount of RNA within the procapsid. The plus strand of segment S binds to one of several sites on the outside of the empty procapsid. The RNA enters and the procapsid expands so that the S sites are lost and M sites appear. Packaging of segment M results in the loss of the M sites and the appearance of the L sites. Packaging of L readies the particle for minus-strand synthesis. If any of the segments is less than normal size, packaging of that class of segments continues until the normal content of RNA for that segment is packaged and the binding sites then change.
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Affiliation(s)
- X Qiao
- Department of Microbiology, The Public Health Research Institute, New York, NY 10016, USA
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53
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Juuti JT, Bamford DH. Protein P7 of phage phi6 RNA polymerase complex, acquiring of RNA packaging activity by in vitro assembly of the purified protein onto deficient particles. J Mol Biol 1997; 266:891-900. [PMID: 9086268 DOI: 10.1006/jmbi.1996.0817] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The RNA polymerase complex of double-stranded RNA bacteriophage phi6 is composed of four proteins, P1, P2, P4 and P7. These four proteins are capable of performing all the functions required for the replication of the double-stranded RNAs of the phi6 genome. The polymerase complex containing the three genomic dsRNA segments is the core particle of the phi6 virion. In this study purified protein P7 was found to form highly asymmetric dimers. Using polyclonal anti-P7 antibody, P7 was shown to be accessible on the surface of the nucleocapsid. Treatment of nucleocapsids with polyclonal anti-P7 antibody released coat protein P8 with ensuing activation of the plus strand RNA synthesis from the resulting core particles. Purified P7 could be assembled onto particles lacking P7 and particles lacking both P2 (RNA polymerase) and P7. In both cases RNA packaging activity was acquired. Assembly of P7 onto deficient particles took place also in the absence of host proteins. Protein P7 is known to be necessary for stable packaging of the three genomic phi6 plus strand RNAs into preformed polymerase complex particles. Additionally, protein P7 seems to be involved in the regulation of plus strand synthesis (i.e. transcription) as a fidelity factor. Particles lacking protein P7 produce anomalous size transcripts. Analysis of the polymerase complex stability revealed that proteins P2, P4 and P7 are independently associated with the major structural protein P1. The number of P7 molecules in one virion was estimated to be 60 and a location at the 5-fold symmetry position is proposed.
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Affiliation(s)
- J T Juuti
- Department of Biosciences, University of Helsinki, Finland
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54
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Lawton JA, Estes MK, Prasad BV. Three-dimensional visualization of mRNA release from actively transcribing rotavirus particles. NATURE STRUCTURAL BIOLOGY 1997; 4:118-21. [PMID: 9033591 DOI: 10.1038/nsb0297-118] [Citation(s) in RCA: 171] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
MESH Headings
- Animals
- Cell Line
- Microscopy, Electron
- Models, Molecular
- Nucleic Acid Conformation
- RNA, Double-Stranded/chemistry
- RNA, Double-Stranded/metabolism
- RNA, Double-Stranded/ultrastructure
- RNA, Messenger/chemistry
- RNA, Messenger/metabolism
- RNA, Messenger/ultrastructure
- RNA, Viral/chemistry
- RNA, Viral/metabolism
- RNA, Viral/ultrastructure
- Rotavirus/metabolism
- Rotavirus/ultrastructure
- Transcription, Genetic
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55
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Prasad BV, Rothnagel R, Zeng CQ, Jakana J, Lawton JA, Chiu W, Estes MK. Visualization of ordered genomic RNA and localization of transcriptional complexes in rotavirus. Nature 1996; 382:471-3. [PMID: 8684490 DOI: 10.1038/382471a0] [Citation(s) in RCA: 176] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In double-stranded-RNA (dsRNA) viruses found in animals, bacteria and yeast, the genome is transcribed within the structurally intact core of the virion with extraordinary efficiency. The structural organization of the genome and the enzymes involved in the transcription inside any of these viruses, critical for understanding this process, is not known. Here we report what we believe is the first three-dimensional characterization of the viral genome and the transcription complex in a prototypical dsRNA virus. Rotavirus is a large (diameter 1,000 A) icosahedral virus composed of three capsid protein layers and 11 dsRNA segments. It is the most important cause of gastroenteritis in children, accounting for over a million deaths annually. We show that viral dsRNA forms a dodecahedral structure in which the RNA double helices, interacting closely with the inner capsid layer, are packed around the enzyme complex located at the icosahedral 5-fold axes. The ordered RNA accounts for about 4,500 out of a total 18,525 base pairs in the genome, the largest amount of icosahedrally ordered RNA observed in any virus structure to date. We propose that the observed organization of the dsRNA is conducive for an orchestrated movement of the RNA relative to the enzyme complex during transcription.
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Affiliation(s)
- B V Prasad
- Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030, USA
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56
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Paatero AO, Syväoja JE, Bamford DH. Double-stranded RNA bacteriophage phi 6 protein P4 is an unspecific nucleoside triphosphatase activated by calcium ions. J Virol 1995; 69:6729-34. [PMID: 7474083 PMCID: PMC189583 DOI: 10.1128/jvi.69.11.6729-6734.1995] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Double-stranded RNA bacteriophage phi 6 has an envelope surrounding the nucleocapsid (NC). The NC is composed of a surface protein, P8, and proteins P1, P2, P4, and P7, which form a dodecahedral polymerase complex enclosing the segmented viral genome. Empty polymerase complex particles (procapsids) package positive-sense viral single-stranded RNAs provided that energy is available in the form of nucleoside triphosphates (NTPs). Photoaffinity labelling of both the NC and the procapsid has earlier been used to show that ATP binds to protein P4 and that the NC hydrolyzes NTPs. Using the NC and the NC core particles (NCs lacking surface protein P8) and purified protein P4, we demonstrate here that multimeric P4 is the active NTPase. Isolation of multimeric P4 is successful only in the presence of NTPs. The activity of P4 is the same in association with the viral particles as it is in pure form. P4 is an unspecific NTPase hydrolyzing ribo-NTPs, deoxy NTPs, and dideoxy NTPs to the corresponding nucleoside diphosphates. The Km of the reaction for ATP, GTP, and UTP is around 0.2 to 0.3 mM. The NTP hydrolysis by P4 absolutely requires residual amounts of Mg2+ ions and is greatly activated when the Ca2+ concentration reaches 0.5 mM. Competition experiments indicate that Mg2+ and Ca2+ ions have approximately equal binding affinities for P4. They might compete for a common binding site. The nucleotide specificity and enzymatic properties of the P4 NTPase are similar to the NTP hydrolysis reaction conditions needed to translocate and condense the viral positive-sense RNAs to the procapsid particle.
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Affiliation(s)
- A O Paatero
- Department of Biosciences, University of Helsinki, Finland
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57
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Qiao X, Qiao J, Mindich L. Interference with bacteriophage phi 6 genomic RNA packaging by hairpin structures. J Virol 1995; 69:5502-5. [PMID: 7636995 PMCID: PMC189401 DOI: 10.1128/jvi.69.9.5502-5505.1995] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Bacteriophage phi 6 has a genome of three segments of double-stranded RNA enclosed in a procapsid composed of four different proteins. The preformed procapsid is capable of packaging plus-strand transcripts of the genomic segments in an in vitro reaction. Minus-strand synthesis within the procapsid then results in the production of the double-stranded RNA genome. When plus-strand transcripts contain strong hairpin structures near the 3' ends, they are subject to heterologous recombination to remove the hairpins. We now find that the sequences bounded by the hairpins as well as those 3' to them are excluded from particles in packaging reactions. This finding implies that packaging occurs from the 5' end and that the explanation for the facilitation of recombination by the hairpin structures is the lack of entry of the 3' ends rather than a difficulty of progressing through the hairpin by the phage polymerase. Packaging of segment M is dependent on the packaging of segment S. An S segment containing a strong hairpin is able to facilitate the packaging of segment M. This result implies that there is more than one entry pore into the procapsid.
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Affiliation(s)
- X Qiao
- Department of Microbiology, Public Health Research Institute, New York, New York 10016, USA
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58
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Frilander M, Poranen M, Bamford DH. The large genome segment of dsRNA bacteriophage phi6 is the key regulator in the in vitro minus and plus strand synthesis. RNA (NEW YORK, N.Y.) 1995; 1:510-518. [PMID: 7489512 PMCID: PMC1482425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Bacteriophage phi6 is a double-stranded RNA (dsRNA) virus that has a genome composed of three linear dsRNA segments (L, M, S). These are encapsidated into a dodecahedral procapsid particle consisting of proteins P1, P2, P4, and P7. Empty preformed procapsids are able to package the plus-sense single-stranded RNA (ssRNA) of each genome segment, to synthesize the corresponding minus strands ("replication") to form dsRNA segments, and to continue to the plus strand synthesis ("transcription") in which the dsRNA segments are used as templates in production of plus-sense ssRNA. In this study, we have investigated the requirements for the switch-on of minus and plus strand syntheses. We show that there exists an inverse relationship between regulation of the ssRNA packaging and minus strand synthesis. The packaging of single-stranded l, which has previously been shown to be packaged as the last, is the necessary signal for the onset of the minus strand synthesis. The absolute requirement for plus strand synthesis is minus strand synthesis of l, but in addition, the minus strand synthesis of m and the packaging of s segment are needed for efficient plus strand synthesis. Furthermore, the second nucleotide at the 5'-end of each segment regulates the extent of the transcription.
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Affiliation(s)
- M Frilander
- Department of Biosciences, University of Helsinki, Finland
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59
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Qiao X, Casini G, Qiao J, Mindich L. In vitro packaging of individual genomic segments of bacteriophage phi 6 RNA: serial dependence relationships. J Virol 1995; 69:2926-31. [PMID: 7707518 PMCID: PMC188991 DOI: 10.1128/jvi.69.5.2926-2931.1995] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Bacteriophage phi 6 has a genome of three segments of double-stranded RNA enclosed in a procapsid composed of four different proteins. The preformed procapsid is capable of packaging plus-strand transcripts of the genomic segments in an in vitro reaction. The packaging of the three segments shows a strong order of dependence in that segment S packages alone, but segment M requires S and and segment L requires S and M for efficient packaging. Packaging of individual segments is dependent on unique packaging sequences of about 200 nucleotides near the 5' ends of the segments. Deletions that invade these regions destroy packaging competence for the particular segment and for the dependent segments as well. In the presence of 2 mM phosphate and at magnesium ion concentrations above 4 mM, packaging becomes progressively more independent and ultimately nonspecific with respect to phi 6 sequences.
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Affiliation(s)
- X Qiao
- Department of Microbiology, Public Health Research Institute, New York, New York 10016, USA
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60
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Affiliation(s)
- W K Joklik
- Department of Microbiology, Duke University Medical Center, Durham, North Carolina 27710
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61
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Mindich L. Heterologous recombination in the segmented dsRNA genome of bacteriophage Φ6. SEMINARS IN VIROLOGY 1995; 6:75-83. [PMID: 32288440 PMCID: PMC7129777 DOI: 10.1016/s1044-5773(05)80011-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The genome of bacteriophage Φ6 is composed of three unique segments of double-stranded RNA packaged within a procapsid. One segment can recombine with another in regions that share little sequence similarity. Although the recombination is therefore heterologous, the crossover points usually consist of two to six identical nucleotides. The frequency of recombinants is enhanced by conditions that prevent or hinder the minus strand synthesis of a single plus strand segment. Recombination serves as a repair system as well as a means of changing the genetic structure of the virus. The reaction can be studied in an in-vitro packaging and replication system involving purified procapsids and ssRNA. Although there are striking differences in the mechanisms of recombination in RNA viruses, there are also strong similarities. All seem to use a copy-choice template switching action for recombination. The Φ6 system is a useful model for the recombination of other segmented double-stranded RNA viruses such as the Reoviridae.
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Affiliation(s)
- Leonard Mindich
- Department of Microbiology, Public Health Research Institute, 455 First Avenue, New York, NY 10016, USA
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62
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Bamford DH, Ojala PM, Frilander M, Walin L, Bamford JK. [25] Isolation, purification, and function of assembly intermediates and subviral particles of bacteriophages PRD1 and σ6. MICROBIAL GENE TECHNIQUES 1995. [DOI: 10.1016/s1067-2389(06)80028-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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63
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Chen D, Zeng CQ, Wentz MJ, Gorziglia M, Estes MK, Ramig RF. Template-dependent, in vitro replication of rotavirus RNA. J Virol 1994; 68:7030-9. [PMID: 7933085 PMCID: PMC237140 DOI: 10.1128/jvi.68.11.7030-7039.1994] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
A template-dependent, in vitro rotavirus RNA replication system was established. The system initiated and synthesized full-length double-stranded RNAs on rotavirus positive-sense template RNAs. Native rotavirus mRNAs or in vitro transcripts, with bona fide 3' and 5' termini, derived from rotavirus cDNAs functioned as templates. Replicase activity was associated with a subviral particle containing VP1, VP2, and VP3 and was derived from native virions or baculovirus coexpression of rotavirus genes. A cis-acting signal involved in replication was localized within the 26 3'-terminal nucleotides of a reporter template RNA. Various biochemical and biophysical parameters affecting the efficiency of replication were examined to optimize the replication system. A replication system capable of in vitro initiation has not been previously described for Reoviridae.
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Affiliation(s)
- D Chen
- Division of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030
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64
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Johnson MD, Mindich L. Plasmid-directed assembly of the lipid-containing membrane of bacteriophage phi 6. J Bacteriol 1994; 176:4124-32. [PMID: 8021194 PMCID: PMC205612 DOI: 10.1128/jb.176.13.4124-4132.1994] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The nucleocapsid of bacteriophage phi 6 is enveloped within a lipid-containing membrane. The membrane is composed of proteins P3, P6, P9, P10, and P13 and phospholipids. The relationship between membrane protein P9 and morphogenetic protein P12 was studied in the absence of phage infection. cDNA copies of genes 9 and 12 were expressed on plasmids in Pseudomonas syringae pv. phaseolicola. Immunoblotting demonstrated the presence of protein P9 in strains carrying both gene 9 and gene 12 but not in strains with gene 9 alone. In the absence of P12, P9 was found to be unstable. Simultaneous synthesis of proteins P9 and P12 led to the formation of a low-density P9 particle having a buoyant density similar to that of precursor structures composed of phospholipid and proteins isolated from phi 6-infected cells. These results are consistent with results of previous genetic experiments suggesting that P9 and P12 are necessary and sufficient for the formation of the phi 6 envelope. Extensions of P9 at the C terminus do not impair particle formation; however, N-terminal extensions or C-terminal deletions that extend into the hydrophobic region of P9 do impair particle formation.
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Affiliation(s)
- M D Johnson
- Department of Microbiology, Public Health Research Institute, New York, New York 10016
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65
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Onodera S, Qiao X, Gottlieb P, Strassman J, Frilander M, Mindich L. RNA structure and heterologous recombination in the double-stranded RNA bacteriophage phi 6. J Virol 1993; 67:4914-22. [PMID: 8331732 PMCID: PMC237879 DOI: 10.1128/jvi.67.8.4914-4922.1993] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Bacteriophage phi 6 has a genome of three segments of double-stranded RNA, designated L, M, and S. A 1.2-kbp kanamycin resistance gene was inserted into segment M but was shown to be genetically unstable because of a high recombination rate between segment M and the 3' ends of segments S and L. The high rate of recombination is due to complementary homopolymer tracts bounding the kan gene. Removal of one arm of this potential hairpin stabilizes the insertion. The insertion of a 241- or 427-bp lacZ' gene into segment M leads to a stable Lac+ phage. The insertion of the same genes bounded by complementary homopolymer arms leads to recombinational instability. A stable derivative of this phage was shown to have lost one of the homopolymer arms. Several other conditions foster recombination. The truncation of a genomic segment at the 3' end prevents replication, but such a damaged molecule can be rescued by recombination. Similarly, insertion of the entire 3-kb lacZ gene prevents normal formation of virus, but the viral genes can be rescued by recombination. It appears that conditions leading to the retardation or absence of replication of a particular genomic segment facilitate recombinational rescue.
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MESH Headings
- Bacteriophage T7/enzymology
- Bacteriophage phi 6/genetics
- Base Sequence
- Cloning, Molecular
- DNA
- DNA, Viral/genetics
- DNA, Viral/metabolism
- DNA-Directed RNA Polymerases/metabolism
- Electrophoresis, Agar Gel
- Models, Genetic
- Models, Structural
- Molecular Sequence Data
- Oligodeoxyribonucleotides
- Pseudomonas/genetics
- RNA, Double-Stranded/genetics
- RNA, Double-Stranded/isolation & purification
- RNA, Viral/genetics
- RNA, Viral/isolation & purification
- RNA, Viral/metabolism
- Recombination, Genetic
- Restriction Mapping
- Transcription, Genetic
- Viral Plaque Assay
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Affiliation(s)
- S Onodera
- Department of Microbiology, Public Health Research Institute, New York, New York 10016
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66
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Ojala PM, Juuti JT, Bamford DH. Protein P4 of double-stranded RNA bacteriophage phi 6 is accessible on the nucleocapsid surface: epitope mapping and orientation of the protein. J Virol 1993; 67:2879-86. [PMID: 7682630 PMCID: PMC237613 DOI: 10.1128/jvi.67.5.2879-2886.1993] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Protein P4, an early protein of double-stranded RNA bacteriophage phi 6, is a component of the virion-associated RNA polymerase complex and possesses a nucleoside triphosphate (NTP) phosphohydrolase activity. We have produced and characterized a panel of 20 P4-specific monoclonal antibodies. Epitope mapping using truncated molecules of recombinant P4 revealed seven linear epitopes. The accessibility of the epitopes on the phi 6 nucleocapsid (NC) surface showed that at least the C terminus and an internal domain, containing the consensus sequence for NTP binding, protrude the NC shell. Four of the NC-binding antibodies distorted the integrity of the NC by releasing protein P4 and the major NC surface protein P8. This finding suggests a close contact between these two proteins. The dissociation of the NC led to the activation of the virion-associated RNA polymerase. The multimeric status of the recombinant P4 was similar to that of the virion-associated P4, indicating that no accessory virus proteins are needed for its multimerization.
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Affiliation(s)
- P M Ojala
- Department of Genetics, University of Helsinki, Finland
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67
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Kenney JM, Hantula J, Fuller SD, Mindich L, Ojala PM, Bamford DH. Bacteriophage phi 6 envelope elucidated by chemical cross-linking, immunodetection, and cryoelectron microscopy. Virology 1992; 190:635-44. [PMID: 1519356 DOI: 10.1016/0042-6822(92)90901-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Bacteriophage phi 6 is an enveloped dsRNA virus which infects the plant pathogenic Pseudomonas syringae bacterium. Using low dose cryoelectron microscopy we show that the nucleocapsid, spikeless virion, and intact virion have radii of 29, 35, and 43 nm, respectively. Thus, the membrane is 6 nm thick and the surface spikes of the receptor binding protein P3 extend 8 nm from the membrane surface. Cross-linking, immunological, and complementation evidence suggest that the spikes are formed of multimeric P3 molecules and that P3 is associated with membrane-bound protein P6. We observe that the envelope can accommodate up to 400 molecules of P3 but that the average virion contains less than one-fourth of this amount. Assembly of a very small number of P3 or truncated P3 molecules onto inactive virions restores infectivity, showing that only a few spikes are necessary for receptor binding and membrane fusion.
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Affiliation(s)
- J M Kenney
- Biological Structures and Biocomputing Programme, European Molecular Biology Laboratory, Heidelberg, Germany
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68
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Gottlieb P, Strassman J, Mindich L. Protein P4 of the bacteriophage phi 6 procapsid has a nucleoside triphosphate-binding site with associated nucleoside triphosphate phosphohydrolase activity. J Virol 1992; 66:6220-2. [PMID: 1326667 PMCID: PMC283676 DOI: 10.1128/jvi.66.10.6220-6222.1992] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Bacteriophage phi 6 contains three segments of double-stranded RNA. The procapsid consists of proteins P1, P2, P4, and P7, which are encoded by the viral L segment. cDNA copies of this segment have been cloned into plasmids that direct the production of these proteins, which assemble into polyhedral procapsids. These procapsids are capable of packaging plus-sense phi 6 RNA in the presence of nucleoside triphosphate and synthesizing the complementary minus strand to form double-stranded RNA. In this article, we report the presence of a nucleotide-binding site in protein P4. The viral procapsid and nucleocapsid exhibit a nucleoside triphosphate phosphohydrolase activity that converts nucleoside triphosphates into nucleoside diphosphates.
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Affiliation(s)
- P Gottlieb
- Department of Microbiology, Public Health Research Institute, New York, New York 10016
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69
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Modak S, Sampath L, Miller HS, Millman I. Rapid inactivation of infectious pathogens by chlorhexidine-coated gloves. Infect Control Hosp Epidemiol 1992; 13:463-71. [PMID: 1325495 DOI: 10.1086/646574] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Gloves containing chlorhexidine gluconate in an instant-release matrix on their inner surface (CHG gloves) were tested to determine their ability to rapidly inactivate infectious pathogens that may permeate or leak through the latex surface. DESIGN CHG gloves were exposed for 1 to 10 minutes to blood or media containing infectious pathogens (e.g., bacteria, fungi, parasites, and viruses) as well as to lymphocytes and macrophages that are known to be the primary carriers of human immunodeficiency virus (HIV). Inactivation of pathogens was determined either by in vitro assay or in vivo infectivity. Stressed control and CHG glove fingers were submerged in a viral pool (retrovirus or bacteriophage) and after a set time, the glove interiors were checked for presence of permeated virions. RESULTS CHG gloves rapidly inactivate all the pathogens tested including retrovirus and hepatitis B virus (90% to 100%). In the stressed glove fingers, live virus was detected in 26% of the control group but not in any of the CHG group. CONCLUSIONS The use of CHG gloves may reduce the risk of exposure to infectious fluid-borne pathogens should the integrity of the latex barrier be compromised by overt failure or by permeation of viruses. Rapid destruction of lymphocytes and macrophages may facilitate inactivation of HIV associated with these cells. Tests have shown that CHG coating does not alter physical properties of the glove, and, furthermore, CHG gloves do not show potential for dermal irritation or sensitization.
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Affiliation(s)
- S Modak
- Department of Surgery, Columbia University College of Physicians and Surgeons, New York, NY
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70
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Modak S, Sampath L, Miller HSS, Millman I. Rapid Inactivation of Infectious Pathogens by Chlorhexidine-Coated Gloves. Infect Control Hosp Epidemiol 1992. [DOI: 10.2307/30145260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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71
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Frilander M, Gottlieb P, Strassman J, Bamford DH, Mindich L. Dependence of minus-strand synthesis on complete genomic packaging in the double-stranded RNA bacteriophage phi 6. J Virol 1992; 66:5013-7. [PMID: 1629962 PMCID: PMC241356 DOI: 10.1128/jvi.66.8.5013-5017.1992] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Bacteriophage phi 6 has a segmented genome consisting of three pieces of double-stranded RNA (dsRNA). The viral procapsid is the structure that packages plus strands, synthesizes the complementary negative strands to form dsRNA, and then transcribes dsRNA to form plus-strand message. The minus-strand synthesis of a particular genomic segment is dependent on prior packaging of the other segments. The 5' end of the plus strand is necessary and sufficient for packaging, while the normal 3' end is necessary for synthesis of the negative strand. We have now investigated the ability of truncated RNA segments which lack the normal 3' end of the molecules to stimulate the synthesis of minus strands of the other segments. Fragments missing the normal 3' ends were able to stimulate the minus-strand synthesis of intact heterologous segments. Minus-strand synthesis of one intact segment could be stimulated by the presence of two truncated nonreplicating segments. The 5' fragments of each single-stranded genomic segment can compete with homologous full-length single-stranded genomic segments in minus-strand synthesis reactions, suggesting that there is a specific binding site in the procapsid for each segment.
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Affiliation(s)
- M Frilander
- Department of Genetics, University of Helsinki, Finland
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72
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Gottlieb P, Strassman J, Qiao X, Frilander M, Frucht A, Mindich L. In vitro packaging and replication of individual genomic segments of bacteriophage phi 6 RNA. J Virol 1992; 66:2611-16. [PMID: 1560520 PMCID: PMC241014 DOI: 10.1128/jvi.66.5.2611-2616.1992] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The genome of bacteriophage phi 6 contains three segments of double-stranded RNA. Procapsid structures whose formation was directed by cDNA copies of the large genomic segment are capable of packaging the three viral message sense RNAs in the presence of ATP. Addition of UTP, CTP, and GTP results in the synthesis of minus strands to form double-stranded RNA. In this report, we show that procapsids are capable of taking up any of the three plus-strand single-stranded RNA segments independently of the others. In manganese-containing buffers, synthesis of the corresponding minus strand takes place. In magnesium-containing buffers, individual message sense viral RNA segments were packaged, but minus-strand replication did not take place unless all three viral single-stranded RNA segments were packaged. Since the conditions of packaging in magnesium buffer more closely resemble those in vivo, these results indicated that there is no specific order or dependence in packaging and that replication is regulated so that it does not begin until all segments are in place.
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Affiliation(s)
- P Gottlieb
- Department of Microbiology, Public Health Research Institute, New York, New York 10016
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73
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Mindich L, Qiao X, Onodera S, Gottlieb P, Strassman J. Heterologous recombination in the double-stranded RNA bacteriophage phi 6. J Virol 1992; 66:2605-10. [PMID: 1560519 PMCID: PMC241013 DOI: 10.1128/jvi.66.5.2605-2610.1992] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Bacteriophage phi 6 contains three double-stranded RNA genomic segments. We have constructed a virus with an insertion of a kanamycin resistance gene in genomic RNA segment M. The virus forms small, turbid plaques, and its genome is unstable. Virus from a single plaque contained from about 0.1 to 10% large clear-plaque forms of the virus; these were usually missing the kanamycin resistance gene, and in many cases, the resulting segment M was larger or smaller than its normal size. Sequence analysis of the genomic RNA of the apparent deletions showed that they were formed by recombination events between segment M and either segment S or L. These heterologous recombination events resulted in the loss of the kanamycin resistance gene from segment M and the replacement of the 3' end of segment M with the 3' end of segment S or L. Although the 3' ends of the single-stranded RNA transcripts of the genomic segments appear to have extensive secondary structure, the sequences at the 3' ends are not involved in the specificity of genomic packaging.
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Affiliation(s)
- L Mindich
- Department of Microbiology, Public Health Research Institute, New York, New York 10016
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74
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Onodera S, Olkkonen VM, Gottlieb P, Strassman J, Qiao XY, Bamford DH, Mindich L. Construction of a transducing virus from double-stranded RNA bacteriophage phi6: establishment of carrier states in host cells. J Virol 1992; 66:190-6. [PMID: 1727482 PMCID: PMC238275 DOI: 10.1128/jvi.66.1.190-196.1992] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Bacteriophage phi 6 contains three double-stranded RNA (dsRNA) genomic segments. We have constructed a plasmid that contains a cDNA copy of the middle (M) segment, with a gene for kanamycin resistance (kan) inserted into the PstI site. A transcript of this cDNA was incorporated in vitro into procapsids along with natural transcripts of the S and L segments. The procapsids were coated with nucleocapsid surface protein P8 and transfected into Pseudomonas syringae pv. phaseolicola. The resulting infectious virus, phi 6 K1, was found to contain an M segment that was 1.2 kbp larger than the normal 4.1 kbp. K1 formed small, turbid plaques, and its genome was unstable. Preparations of K1 contained from about 0.1 to 10% large, clear-plaque forms of the virus which were usually missing the kan gene, and in some cases, the resulting segment M was smaller than its normal size. Cells picked from lawns of host cells infected with K1 yielded colonies that were resistant to kanamycin (Kan). These colonies could be passaged on kanamycin-containing medium. The cells were found to contain large amounts of dsRNA corresponding to the viral genomic segments. Some strains continued to produce viable phage, while others lost this ability. One strain completely lost the small genomic segment S. Approximately 1 in 10,000 infected cells acquired the carrier state with the original phage isolate K1. However, we isolated a viral mutant that was able to induce the carrier state in 10 to 20% of the infected cells. The ability to use drug resistance as a test for the carrier state makes this system very useful for the study of the mechanisms of induction of persistent infections.
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Affiliation(s)
- S Onodera
- Department of Microbiology, Public Health Research Institute, New York, New York 10016
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75
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Labbé M, Charpilienne A, Crawford SE, Estes MK, Cohen J. Expression of rotavirus VP2 produces empty corelike particles. J Virol 1991; 65:2946-52. [PMID: 1851866 PMCID: PMC240932 DOI: 10.1128/jvi.65.6.2946-2952.1991] [Citation(s) in RCA: 152] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The complete VP2 gene of bovine rotavirus strain RF has been inserted into the baculovirus transfer vector pVL941 under the control of the polyhedrin promoter. Cotransfection of Spodoptera frugiperda 9 cells with wild-type baculovirus DNA and transfer vector DNA led to the formation of recombinant baculoviruses which contain bovine rotavirus gene 2. Infection of S. frugiperda cells with this recombinant virus resulted in the production of a protein similar in size and antigenic properties to the authentic rotavirus VP2. The protein binds double-stranded RNA and DNA in an overlay protein blot assay. Expressed VP2 assembles in the cytoplasm of infected cells in corelike particles 45 nm in diameter. These corelike particles were purified by sucrose gradient centrifugation and found to be devoid of nucleic acid. Coexpression of VP2 and VP6 from heterologous rotavirus strains (bovine and simian) resulted in the formation of single-shelled particles. These results definitively show the existence of an innermost protein shell in rotavirus which is formed independently of other rotavirus proteins. These results have implications for schemes of rotavirus morphogenesis.
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Affiliation(s)
- M Labbé
- Laboratoire de Virologie et d'Immunologie Moléculaire INRA, C.R.J. Domaine de Vilvert, Jouy-en-Josas, France
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76
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Olkkonen VM, Ojala PM, Bamford DH. Generation of infectious nucleocapsids by in vitro assembly of the shell protein on to the polymerase complex of the dsRNA bacteriophage phi 6. J Mol Biol 1991; 218:569-81. [PMID: 2016747 DOI: 10.1016/0022-2836(91)90702-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A method for the in vitro uncoating of the phi 6 nucleocapsid (NC) was developed. The resulting particle, designated as the NC core, containing the genomic double-stranded (ds) RNA segments and the proteins P1, P2, P4 and P7, was not infectious but had a highly enhanced in vitro transcriptase activity compared to that of the intact NC. The NC shell protein P8 was purified by immunoaffinity chromatography, and it was shown to self-assemble to shell-like structures upon addition of calcium ions. The conditions for the self-assembly of the shell were optimized. Shell reassembly on to the NC cores restored the infectivity but resulted in a decrease of transcriptase activity. No reassembly of the shell on to RNA-less cores (procapsids) produced from a cDNA construction in Escherichia coli was observed. Our results suggest that the intracellular uncoating of the NC is the event activating the phi 6 dsRNA transcriptase and that the NC shell is necessary for infectivity, probably for the passage of the NC through the host cytoplasmic membrane. Packaging of the dsRNA segments into the procapsid appears to be a prerequisite for NC shell assembly.
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Affiliation(s)
- V M Olkkonen
- Department of Genetics, University of Helsinki, Finland
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77
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Gottlieb P, Strassman J, Frucht A, Qiao XY, Mindich L. In vitro packaging of the bacteriophage phi 6 ssRNA genomic precursors. Virology 1991; 181:589-94. [PMID: 2014638 DOI: 10.1016/0042-6822(91)90892-f] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bacteriophage phi 6 contains three segments of double-stranded RNA within a nucleocapsid. Plasmids containing cDNA copies of the large genomic segment direct the synthesis of viral proteins that assemble into procapsids in Escherichia coli or Pseudomonas phaseolicola. These structures are dodecahedral assemblages of proteins P1, P2, P4, and P7. We report in this paper that these particles are capable of packaging viral single-stranded plus-sense RNA in vitro. The packaging reaction requires the presence of ATP or dATP. Synthesis of minus strands takes place within this filled procapsid in the presence of all four nucleoside triphosphates. Packaged ssRNA is found to be protected from added ribonuclease.
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Affiliation(s)
- P Gottlieb
- Department of Microbiology, Public Health Research Institute New York, New York 10016
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78
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Olkkonen VM, Gottlieb P, Strassman J, Qiao XY, Bamford DH, Mindich L. In vitro assembly of infectious nucleocapsids of bacteriophage phi 6: formation of a recombinant double-stranded RNA virus. Proc Natl Acad Sci U S A 1990; 87:9173-7. [PMID: 2251260 PMCID: PMC55126 DOI: 10.1073/pnas.87.23.9173] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A system is described for assembling infectious bacteriophage phi 6 nucleocapsids in vitro. Procapsids encoded by cDNA copies of genomic segment L in Escherichia coli were used to package and replicate viral RNA segments. The resulting filled particles were shown to be capable of infecting host cell spheroplasts after incubation with purified nucleocapsid shell protein P8. The infected spheroplasts yielded infectious virions. A modified cDNA-derived RNA segment was inserted into virions by this method. The resulting infectious virions contained the same 4-base-pair deletion as the modified cDNA. These findings support the contention that the preformed procapsids are the "machine" that replicates the phi 6 genome, by showing that the cDNA-derived procapsids are competent to package and replicate RNA properly.
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Affiliation(s)
- V M Olkkonen
- Department of Genetics, University of Helsinki, Finland
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