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Dong J, Chen Y, Xie Y, Cao M, Fu S, Wu J. The Identification of Viral Pathogens in a Physostegia virginiana Plant Using High-Throughput RNA Sequencing. Viruses 2023; 15:1972. [PMID: 37766378 PMCID: PMC10534606 DOI: 10.3390/v15091972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/18/2023] [Accepted: 09/20/2023] [Indexed: 09/29/2023] Open
Abstract
Physostegia virginiana is an important ornamental and cut-flower plant in China. Its commonly used method of clonal propagation leads to virus accumulation in this plant. However, which viruses can infect the Physostegia virginiana plant remains to be illuminated. In this work, five viral pathogens in a Physostegia virginiana plant with virus-like symptoms of yellow, shriveled, and curled leaves were identified using RNA-seq, bioinformatics, and molecular biological techniques. These techniques allowed us to identify five viruses comprising one known alfalfa mosaic virus (AMV) and four novel viruses. The novel viruses include a virus belonging to the genus Fabavirus, temporarily named Physostegia virginiana crinkle-associated virus 1 (PVCaV1); two viruses belonging to the genus Caulimovirus, temporarily named Physostegia virginiana caulimovirus 1 and 2 (PVCV1 and PVCV2); and a virus belonging to the genus Fijivirus, temporarily named Physostegia virginiana fijivirus (PVFV). The genome sequences of PVCaV1, PVCV1, and PVCV2, and the partial genome sequence of PVFV were identified. Genome organizations and genetic evolutionary relationships of all four novel viruses were analyzed. PVCaV1 has a relatively close evolutionary relationship with five analyzed fabiviruses. PVCV1 and PVCV2 have separately a closest evolutionary relationship with lamium leaf distortion-associated virus (LLDAV) and figwort mosaic virus (FMV), and PVFV has a close evolutionary relationship with the five analyzed fijiviruses. Additionally, PVCaV1 can infect Nicotiana benthamiana plants via friction inoculation. The findings enrich our understanding of Physostegia virginiana viruses and contribute to the prevention and control of Physostegia virginiana viral diseases.
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Affiliation(s)
- Jinxi Dong
- Hainan Institute, Zhejiang University, Sanya 572025, China; (J.D.); (Y.C.)
- State Key Laboratory of Rice Biology, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China;
| | - Yuanling Chen
- Hainan Institute, Zhejiang University, Sanya 572025, China; (J.D.); (Y.C.)
- State Key Laboratory of Rice Biology, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China;
| | - Yi Xie
- State Key Laboratory of Rice Biology, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China;
| | - Mengji Cao
- National Citrus Engineering and Technology Research Center, Citrus Research Institute, Southwest University, Chongqing 400712, China
| | - Shuai Fu
- Research Center for Biological Computation, Zhejiang Lab, Hangzhou 311100, China
| | - Jianxiang Wu
- Hainan Institute, Zhejiang University, Sanya 572025, China; (J.D.); (Y.C.)
- State Key Laboratory of Rice Biology, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China;
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Stewart LR, Willman M, Marty D, Cole AE, Willie K. Critical residues for proteolysis activity of maize chlorotic dwarf virus (MCDV) 3C-like protease and comparison of activity of orthologous waikavirus proteases. Virology 2021; 567:57-64. [PMID: 34998226 DOI: 10.1016/j.virol.2021.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 12/21/2021] [Accepted: 12/21/2021] [Indexed: 11/17/2022]
Abstract
Maize chlorotic dwarf virus (MCDV) encodes a 3C-like protease that cleaves the N-terminal polyprotein (R78) as previously demonstrated. Here, we examined amino acid residues required for catalytic activity of the protease, including those in the predicted catalytic triad, amino acid residues H2667, D2704, and C2798, as well as H2817 hypothesized to be important in substrate binding. These and other residues were targeted for mutagenesis and tested for proteolytic cleavage activity on the N-terminal 78 kDa MCDV-S polyprotein substrate to identify mutants that abolished catalytic activity. Mutations that altered the predicted catalytic triad residues and H2817 disrupted MCDV-S protease activity, as did mutagenesis of a conserved tyrosine residue, Y2774. The protease activity and R78 cleavage of orthologs from divergent MCDV isolates MCDV-Tn and MCDV-M1, and other waikavirus species including rice tungro spherical virus (RTSV) and bellflower vein chlorosis virus (BVCV) were also examined.
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Affiliation(s)
- Lucy R Stewart
- USDA ARS Foreign Disease-Weed Science Research Unit, Frederick, MD, 21702, USA.
| | - Matthew Willman
- USDA ARS Corn, Soybean and Wheat Quality Research Unit, Wooster, OH, 44691, USA
| | - DeeMarie Marty
- USDA ARS Corn, Soybean and Wheat Quality Research Unit, Wooster, OH, 44691, USA
| | | | - Kristen Willie
- USDA ARS Corn, Soybean and Wheat Quality Research Unit, Wooster, OH, 44691, USA
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3
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Zhang T, Li C, Cao M, Wang D, Wang Q, Xie Y, Gao S, Fu S, Zhou X, Wu J. A Novel Rice Curl Dwarf-Associated Picornavirus Encodes a 3C Serine Protease Recognizing Uncommon EPT/S Cleavage Sites. Front Microbiol 2021; 12:757451. [PMID: 34721366 PMCID: PMC8549817 DOI: 10.3389/fmicb.2021.757451] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 09/21/2021] [Indexed: 11/13/2022] Open
Abstract
Picornaviruses cause diseases in a wide range of vertebrates, invertebrates and plants. Here, a novel picornavirus was identified by RNA-seq technology from rice plants showing dwarfing and curling symptoms, and the name rice curl dwarf-associated virus (RCDaV) is tentatively proposed. The RCDaV genome consists of an 8,987 nt positive-stranded RNA molecule, excluding a poly(A) tail, that encodes two large polyproteins. Using in vitro cleavage assays, we have identified that the RCDaV 3C protease (3Cpro) as a serine protease recognizes the conserved EPT/S cleavage site which differs from the classic Q(E)/G(S) sites cleaved by most picornaviral 3C chymotrypsin-like cysteine proteases. Therefore, we comprehensively deciphered the RCDaV genome organization and showed that the two polyproteins of RCDaV can be cleaved into 12 mature proteins. We found that seven unclassified picornaviruses also encode a 3Cpro similar to RCDaV, and use the highly conserved EPT/S as the cleavage site. The precise genome organizations of these viruses were illustrated. Moreover, RCDaV and the seven unclassified picornaviruses share high sequence identities and similar genome organizations, and cluster into a distinct clade in the order Picornavirales. Our study provides valuable information for the understanding of picornaviral 3Cpros, deciphers the genome organization of a few relatively obscure picornaviruses, and lays the foundation for further pathogenesis research on these viruses.
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Affiliation(s)
- Tianze Zhang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Chenyang Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Mengji Cao
- National Citrus Engineering and Technology Research Center, Citrus Research Institute, Southwest University, Beibei, China
| | - Dan Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Qi Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yi Xie
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Shibo Gao
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Shuai Fu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China.,State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jianxiang Wu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China.,Hainan Research Institute of Zhejiang University, Hainan, China
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Rodamilans B, Shan H, Pasin F, García JA. Plant Viral Proteases: Beyond the Role of Peptide Cutters. FRONTIERS IN PLANT SCIENCE 2018; 9:666. [PMID: 29868107 PMCID: PMC5967125 DOI: 10.3389/fpls.2018.00666] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/30/2018] [Indexed: 05/23/2023]
Abstract
Almost half of known plant viral species rely on proteolytic cleavages as key co- and post-translational modifications throughout their infection cycle. Most of these viruses encode their own endopeptidases, proteases with high substrate specificity that internally cleave large polyprotein precursors for the release of functional sub-units. Processing of the polyprotein, however, is not an all-or-nothing process in which endopeptidases act as simple peptide cutters. On the contrary, spatial-temporal modulation of these polyprotein cleavage events is crucial for a successful viral infection. In this way, the processing of the polyprotein coordinates viral replication, assembly and movement, and has significant impact on pathogen fitness and virulence. In this mini-review, we give an overview of plant viral proteases emphasizing their importance during viral infections and the varied functionalities that result from their proteolytic activities.
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Affiliation(s)
- Bernardo Rodamilans
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | - Hongying Shan
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | - Fabio Pasin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
| | - Juan Antonio García
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
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Stewart LR, Jarugula S, Zhao Y, Qu F, Marty D. Identification of a maize chlorotic dwarf virus silencing suppressor protein. Virology 2017; 504:88-95. [PMID: 28160664 DOI: 10.1016/j.virol.2016.11.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/23/2016] [Accepted: 11/25/2016] [Indexed: 11/27/2022]
Abstract
Maize chlorotic dwarf virus (MCDV), a member of the genus Waikavirus, family Secoviridae, has a 11784 nt (+)ssRNA genome that encodes a 389kDa proteolytically processed polyprotein. We show that the N-terminal 78kDa polyprotein (R78) of MCDV acts as a suppressor of RNA silencing in a well-established assay system. We further demonstrate that R78 is cleaved by the viral 3C-like protease into 51 and 27kDa proteins (p51 and p27), and that p51 is responsible for silencing suppressor activity. Silencing suppressor activity of R78 is conserved in three divergent MCDV strains (MCDV-Severe, MCDV-M1, and MCDV-Tennessee), as well as the waikavirus Bellflower vein chlorosis virus, but was not detected for orthologous protein of Rice tungro spherical virus (RTSV-A) or the similarly-positioned protein from the sequivirus Parsnip yellow fleck virus (PYFV). This is the first identification of a virus suppressor of RNA silencing encoded by a waikavirus.
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Affiliation(s)
- Lucy R Stewart
- USDA-ARS Corn, Soybean and Wheat Quality Research Unit, Wooster, OH, USA; Department of Plant Pathology, Ohio State University, Wooster, OH, USA.
| | - Sridhar Jarugula
- Department of Plant Pathology, Ohio State University, Wooster, OH, USA
| | - Yujing Zhao
- Department of Plant Pathology, Ohio State University, Wooster, OH, USA
| | - Feng Qu
- Department of Plant Pathology, Ohio State University, Wooster, OH, USA
| | - DeeMarie Marty
- USDA-ARS Corn, Soybean and Wheat Quality Research Unit, Wooster, OH, USA
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6
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Seo JK, Kwak HR, Lee YJ, Kim J, Kim MK, Kim CS, Choi HS. Complete genome sequence of bellflower vein chlorosis virus, a novel putative member of the genus Waikavirus. Arch Virol 2015; 160:3139-42. [PMID: 26370789 DOI: 10.1007/s00705-015-2606-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 09/07/2015] [Indexed: 11/28/2022]
Abstract
The complete genome sequence of a new virus isolated from a bellflower (Campanula takesimana) plant was determined. The genome of this virus is composed of monopartite single-stranded RNA of 11,649 nucleotides in length. BLAST searches of protein databases showed that the encoded polyprotein has a maximum amino acid sequence identity of 42% (with 99% coverage) to the polyprotein of the isolate Orissa of rice tungro spherical virus (RTSV; genus Waikavirus). Phylogenetic analysis strongly supports that the identified virus is a member of a new species of the genus Waikavirus. The name bellflower vein chlorosis virus (BVCV) is proposed for this new virus.
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Affiliation(s)
- Jang-Kyun Seo
- Crop Protection Division, National Academy of Agricultural Science, Rural Development Administration, Wanju, 565-851, Republic of Korea.
| | - Hae-Ryun Kwak
- Crop Protection Division, National Academy of Agricultural Science, Rural Development Administration, Wanju, 565-851, Republic of Korea
| | - Ye-ji Lee
- Crop Protection Division, National Academy of Agricultural Science, Rural Development Administration, Wanju, 565-851, Republic of Korea
| | - Jaedeok Kim
- Crop Protection Division, National Academy of Agricultural Science, Rural Development Administration, Wanju, 565-851, Republic of Korea
| | - Mi-Kyeong Kim
- Crop Protection Division, National Academy of Agricultural Science, Rural Development Administration, Wanju, 565-851, Republic of Korea
| | - Chang-Seok Kim
- Crop Protection Division, National Academy of Agricultural Science, Rural Development Administration, Wanju, 565-851, Republic of Korea
| | - Hong-Soo Choi
- Crop Protection Division, National Academy of Agricultural Science, Rural Development Administration, Wanju, 565-851, Republic of Korea.
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8
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Hunnicutt LE, Hunter WB, Cave RD, Powell CA, Mozoruk JJ. Genome sequence and molecular characterization of Homalodisca coagulata virus-1, a novel virus discovered in the glassy-winged sharpshooter (Hemiptera: Cicadellidae). Virology 2006; 350:67-78. [PMID: 16574186 DOI: 10.1016/j.virol.2006.02.034] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 12/14/2005] [Accepted: 02/15/2006] [Indexed: 01/24/2023]
Abstract
The complete nucleotide sequence of a novel single-stranded RNA virus infecting the glassy-winged sharpshooter, Homalodisca coagulata, has been determined. In silico analysis of H. coagulata virus-1 (HoCV-1) revealed a 9321-nt polyadenylated genome encoding two large open reading frames (ORF1 and ORF2) separated by a 182-nt intergenic region (IGR). The deduced amino acid sequence of the 5'-proximal ORF (ORF1, nt 420-5807) exhibited conserved core motifs characteristic of the helicases, cysteine proteases, and RNA-dependent RNA polymerases of other insect-infecting picorna-like viruses. A structural model created using Mfold exposed a series of stem loop (SL) structures immediately preceding the second ORF which are analogous to an internal ribosome entry site (IRES), suggesting that ORF2 begins with a noncognate GCA triplet rather than the canonical AUG. This 3' ORF2 (5990-8740) showed significant similarity to the structural proteins of members of the family Dicistroviridae, particularly those belonging to the genus Cripavirus. Evidence demonstrating relatedness of these viruses regarding genome organization, amino acid sequence similarity, and putative replication strategy substantiate inclusion of HoCV-1 into this taxonomic position.
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Affiliation(s)
- Laura E Hunnicutt
- USDA ARS U.S. Horticultural Research Laboratory, 2001 S. Rock Rd., Ft. Pierce, FL 34945, USA
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9
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Bruenn JA. A structural and primary sequence comparison of the viral RNA-dependent RNA polymerases. Nucleic Acids Res 2003; 31:1821-9. [PMID: 12654997 PMCID: PMC152793 DOI: 10.1093/nar/gkg277] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2002] [Revised: 12/02/2002] [Accepted: 01/22/2003] [Indexed: 12/12/2022] Open
Abstract
A systematic bioinformatic approach to identifying the evolutionarily conserved regions of proteins has verified the universality of a newly described conserved motif in RNA-dependent RNA polymerases (motif F). In combination with structural comparisons, this approach has defined two regions that may be involved in unwinding double-stranded RNA (dsRNA) for transcription. One of these is the N-terminal portion of motif F and the second is a large insertion in motif F present in the RNA-dependent RNA polymerases of some dsRNA viruses.
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Affiliation(s)
- Jeremy A Bruenn
- Department of Biological Sciences, State University of New York, Buffalo, NY 14260, USA.
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10
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Thole V, Hull R. Characterization of a protein from Rice tungro spherical virus with serine proteinase-like activity. J Gen Virol 2002; 83:3179-3186. [PMID: 12466496 DOI: 10.1099/0022-1317-83-12-3179] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The RNA genome of Rice tungro spherical virus (RTSV) is predicted to be expressed as a large polyprotein precursor (Shen et al., Virology 193, 621-630, 1993 ). The polyprotein is processed by at least one virus-encoded protease located adjacent to the C-terminal putative RNA polymerase which shows sequence similarity to viral serine-like proteases. The catalytic activity of this protease was explored using in vitro transcription/translation systems. Besides acting in cis, the protease had activity in trans on precursors containing regions of the 3' half of the polyprotein but did not process a substrate consisting of a precursor of the coat proteins. The substitution mutation of Asp(2735) of the RTSV polyprotein had no effect on proteolysis; however, His(2680), Glu(2717), Cys(2811) and His(2830) proved to be essential for catalytic activity and could constitute the catalytic centre and/or substrate-binding pocket of the RTSV 3C-like protease.
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Affiliation(s)
- Vera Thole
- John Innes Centre, Department of Metabolic Biology1 and Department of Disease and Stress Biology2, Norwich Research Park, Norwich NR4 7UH, UK
| | - Roger Hull
- John Innes Centre, Department of Metabolic Biology1 and Department of Disease and Stress Biology2, Norwich Research Park, Norwich NR4 7UH, UK
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Karasev AV, Han SS, Iwanami T. Satsuma dwarf and related viruses belong to a new lineage of plant picorna-like viruses. Virus Genes 2002; 23:45-52. [PMID: 11556400 DOI: 10.1023/a:1011131328951] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Satsuma dwarf virus (SDV) and two closely related viruses, Citrus mosaic (CiMV), and Naval orange infectious mottling (NIMV), seriously affect citrus varieties grown in Japan and East Asia. All three viruses have icosahedral particles built of two proteins encapsidating two single-stranded genomic RNAs. The natural mode of transmission of these SDV-like viruses is unknown, and they were previously placed among tentative members of the family Comoviridae. Recently, a complete genome of SDV was sequenced, and its replication-related proteins were found only distantly related to those of viruses from the family Comoviridae (Iwanami T., Kondo Y., and Karasev A.V. J Gen Virol 80, 793-797, 1999). Here we present a partial genome sequence for another SDV-like virus, NIMV, and a thorough phylogenetic analysis of the gene products encoded by SDV, CiMV, and NIMV to assess their relationships with picorna-like viruses infecting plants, insects, and vertebrates. The RdRp's of SDV-like viruses form a new lineage, separate from members of Como- and Sequiviridae families. Phylogenetic analysis suggests that SDV-like viruses may represent a new family of plant picorna-like viruses. Sequence analysis of the capsid proteins (CPs) encoded by the SDV-like viruses revealed a region of similarity to CPs of animal calici- and picornaviruses that encompasses the structural core of the eight-strand beta-barrel characteristic of picornaviral CPs. These data suggest that SDV and related bipartite viruses evolved separately from the viruses in the family Comoviridae and that the split of an ancestor, monopartite picorna-like virus genome might have occurred more than once.
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Affiliation(s)
- A V Karasev
- Department of Microbiology and Immunology, Biotechnology Foundation Laboratories at Thomas Jefferson University, Doylestown, PA 18901, USA
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Isogai M, Cabauatan PQ, Masuta C, Uyeda I, Azzam O. Complete nucleotide sequence of the rice tungro spherical virus genome of the highly virulent strain Vt6. Virus Genes 2000; 20:79-85. [PMID: 10766310 DOI: 10.1023/a:1008116408733] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The complete nucleotide sequence of rice tungro spherical virus (RTSV) strain Vt6, originally from Mindanao, the Philippines, with higher virulence to resistant rice cultivars, was determined and compared with the published sequence for the Philippine-type strain A (RTSV-A-Shen). It was reported that RTSV-A was not able to infect a rice resistant cultivar TKM 6 (10). RTSV-Vt6 and RTSV-A-Shen share 90% and 95% homology at nucleotide and amino-acid levels, respectively. The N-terminal leader sequence of RTSV-Vt6 contained a 39-amino acids-region (positions 65 to 103) which was totally different from that of RTSV-A-Shen; the difference resulted from frame shifting by nucleotide insertions and deletions. To confirm the amino-acid sequence differences of the leader polypeptide, the same region was cloned and sequenced using a newly obtained variant of RTSV-type 6, which had been collected in the field of IRRI, and seven field isolates from Mindanao, the Philippines. Since all the sequences of the target region are identical to that of the Vt6 leader polypeptide, the sequence difference in the leader region seems not to correlate with the virulence of Vt6.
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Affiliation(s)
- M Isogai
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University, Morioka, Japan
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Huet H, Mahendra S, Wang J, Sivamani E, Ong CA, Chen L, de Kochko A, Beachy RN, Fauquet C. Near immunity to rice tungro spherical virus achieved in rice by a replicase-mediated resistance strategy. PHYTOPATHOLOGY 1999; 89:1022-1027. [PMID: 18944657 DOI: 10.1094/phyto.1999.89.11.1022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ABSTRACT Rice tungro disease is caused by rice tungro bacilliform virus (RTBV), which is responsible for the symptoms, and rice tungro spherical virus (RTSV), which assists transmission of both viruses by leafhoppers. Transgenic japonica rice plants (Oryza sativa) were produced containing the RTSV replicase (Rep) gene in the sense or antisense orientation. Over 70% of the plants contained one to five copies of the Rep gene, with integration occurring at a single locus in most cases. Plants producing antisense sequences exhibited significant but moderate resistance to RTSV (60%); accumulation of antisense RNA was substantial, indicating that the protection was not of the homology-dependent type. Plants expressing the full-length Rep gene, as well as a truncated Rep gene, in the (+)-sense orientation were 100% resistant to RTSV even when challenged with a high level of inoculum. Accumulation of viral RNA was low, leading us to conclude that RTSV Rep-mediated resistance is not protein-mediated but is of the cosuppression type. Resistance was effective against geographically distinct RTSV isolates. In addition, RTSV-resistant transgenic rice plants were unable to assist transmission of RTBV. Such transgenic plants could be used in an epidemiological approach to combat the spread of the tungro disease.
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