The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Said A. Ghabrial - One of the best experts on this subject based on the ideXlab platform.
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Characterization of a Severe Strain of Cucumber Mosaic Cucumovirus Seedborne in Cowpea
Plant disease, 1998Co-Authors: A. G. Gillaspie, M. R. Hajimorad, Said A. GhabrialAbstract:A new seedborne strain of cucumber mosaic Cucumovirus (CMV) that induces severe symptoms on many cowpea genotypes was detected in Georgia in 1994. This strain, designated CMV-Csb, is asymptomatic on tobacco, but it produces more severe cowpea stunt symptoms when present in combination with blackeye cowpea mosaic potyvirus than do the more prevalent CMV isolates. The new strain is seedborne in cowpea (1.5 to 37%), has no associated satellite RNA, and is classified as a member of subgroup I of CMV strains based on nucleic acid hybridization assays.
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First report of peanut stunt Cucumovirus naturally infecting Desmodium sp.
Plant disease, 1998Co-Authors: A. G. Gillaspie, Said A. GhabrialAbstract:Plant species in the genus Desmodium (Fabaceae) are used as forage and cover crops and include a number of common weeds such as beggarweed (D. tortuosum) and beggarlice (D. intortum). Accessions of the genus are part of the plant genetic resources collection maintained at Griffin, GA. Peanut stunt Cucumovirus (PSV) was detected in naturally infected plants of Desmodium sp. PI 322505 (from Brazil) in a germ plasm regeneration plot by a direct antigen coating-enzyme-linked immunosorbent assay (DAC-ELISA) with an antiserum against PSV strain ER (subgroup I) originally isolated from cowpea in Georgia. The infected plants showed mild mosaic symptoms. Indicator host studies in the greenhouse revealed symptoms characteristic of PSV on Nicotiana tabacum cv. Burley 21 (ringspots and oak leaf pattern), Chenopodium album subsp. amaranticolor (chlorotic local lesions), and Vigna unguiculata (chlorotic spots followed by systemic mild mosaic). These symptomatic indicator plants tested positive for PSV by DAC-ELISA. Gre...
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Evidence for the occurrence of two distinct subgroups of peanut stunt Cucumovirus strains: molecular characterization of RNA3.
Journal of General Virology, 1997Co-Authors: A E Aboul-ata, R. A. Naidu, Said A. GhabrialAbstract:Strains of peanut stunt Cucumovirus (PSV) were classified into two distinct subgroups, I and II, based on Western and Northern blot analyses using antisera and cloned cDNA probes to strains PSV-ER and PSV-W. These results were corroborated by nucleotide sequence analyses of full-length cDNA clones of RNA3 from representative strains of the two subgroups. Whereas the percentage nucleotide sequence identity between PSV-ER (or PSV-J) and PSV-W RNA3s was determined to be 80%, the corresponding value between strains ER and J was 91%, confirming that strains ER and J belong to the same subgroup (subgroup I) whereas strain W belongs to a separate subgroup (subgroup II). PSV-W and PSV-ER RNA3s are 2173 and 2188 nucleotides long, respectively. Each is dicistronic, encoding a putative movement protein (3a protein) and a coat protein (CP). The intercistronic and 5' untranslated region (UTR) sequences of PSV strains, unlike those of cucumber mosaic Cucumovirus (CMV) strains, are highly conserved and thus not useful for distinguishing the two subgroups. However, the 3' UTR sequences of PSV strains, like those of CMV strains, can discriminate between the two subgroups since strains within the same subgroup are 95% identical in their 3' UTRs whereas those in different subgroups are only 74-78% identical. PSV-W and PSV-ER RNA4s were determined to be 994 and 1006 nucleotides long, respectively. PSV 3a and CP genes have higher percentage nucleotide sequence identities to those of tomato aspermy Cucumovirus than to those of CMV.
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Differentiation of Eastern and Western Strains of Peanut Stunt Cucumovirus Based on Satellite RNA Support and Nucleotide Sequence Homology
Phytopathology, 1995Co-Authors: R. A. Naidu, R E Pennington, Said A. GhabrialAbstract:Two western strains of peanut stunt Cucumovirus (PSV), strains W and BV-15, were unable to support the replication of 2 distinct PSV satellite RNAs (satRNAs), or infectious transcripts from full-length satRNA cDNA clones, in either tobacco or several leguminous host species. These 2 strains also did not support the replication of cucumber mosaic Cucumovirus satRNAs in tobacco. However, all 10 eastern PSV strains tested efficiently supported PSV satRNA replication. Strains PSV-W and BV-15 can be further differentiated from the eastern strain PSV-ER by Northern hybridization using cloned cDNA probes to PSV-ER RNAs 1, 2 and 3. Whereas the PSV-ER RNA-specific probes did not hybridize to any PSV-W RNAs, the PSV-ER RNA 3 probe hybridized strongly to PSV-BV-15 RNAs 3 and 4, supporting the finding that strain BV-15 is serologically closely related to the eastern strains. The PSV-ER RNA 2-specific probe, but not the PSV-ER RNA 1-specific probe, hybridized to the respective RNA of PSV-BV-15. The results of Northern hybridization with strain PSV-BV-15 support the contention that strain BV-15 represents a reassortant between western and eastern strains. The lack of cross-hybridization between PSV-ER and PSV-W RNAs in Northern hybridization at high stringency is consistent with finding that the percentages of nucleotide identity between the RNAs of strains PSV-ER and PSV-W were 75, 73, 74 and 74%, respectively, for RNAs 1, 2, 3 and 4. A procedure based on reverse transcription and the polymerase chain reaction (RT-PCR) was developed that utilized primer specific for PSV-ER RNA 2. Restriction enzyme digestion of the RT-PCR products generated distinct restriction patterns that clearly differentiated western from eastern strains.
Robert H Symons - One of the best experts on this subject based on the ideXlab platform.
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stability and competitiveness of interviral recombinant rnas derived from a chimeric Cucumovirus
Virus Research, 2009Co-Authors: Bu-jun Shi, Robert H Symons, Peter PalukaitisAbstract:We previously described interviral recombinant RNAs derived from a chimeric virus having RNAs 1 and 2 of cucumber mosaic virus (CMV) with RNA 3 from the related tomato aspermy virus (TAV) and the 2b gene from either TAV or another strain of CMV. Here, we show that these interviral recombinant RNAs 3 were stable in the infected plants and could co-exist with their wild-type parental viral RNAs in the same plants, but their de novo generations were inhibited in the presence of the wild-type parental viral RNAs. The recombinant viral genomes did not prevent the replication of other viral RNAs or vice versa, but one of the interviral recombinant viruses induced different symptoms in Physalis floridana from those induced by the parental chimeric virus without the interviral RNA 3 recombinant. Factors such as the nature of the 2b gene and/or the presence or absence of competing wild-type parental RNAs influenced the generation of the recombinant RNAs described. Our data provide additional mechanistic insight into generation, stabilization and competition of recombinant viral RNA in infected host plants.
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TWO NOVEL SUBGENOMIC RNAS DERIVED FROM RNA 3 OF TOMATO ASPERMY Cucumovirus
Journal of General Virology, 1997Co-Authors: Bu-jun Shi, S W Ding, Robert H SymonsAbstract:Two abundant subgenomic RNAs, designated RNA 3B and RNA 5, were found to be associated with the V strain of tomato aspermy Cucumovirus (V-TAV). Sequence determination showed that the 3'-terminal 323 nucleotides (nt) of RNA 3B was identical to RNA 5, whereas its 5'-terminal 163 nt was a direct repeat (one nt difference) of the 5'-half of RNA 5, and that both RNAs are completely homologous to the 3'-terminal untranslated region of TAV RNA 3. TAV RNAs 3B and 5 were also detected in the infection of a pseudorecombinant virus consisting of TAV RNA 3 and RNAs 1 and 2 from cucumber mosaic virus. Furthermore, only RNA 5, not RNA 3B, was detected in a TAV mutant in which one of the repeats was deleted from RNA 3. These genetic studies clearly show that both RNA species are derived from TAV RNA 3. However, in contrast to TAV RNAs 4 and 4A, which encode coat protein and 2b protein, respectively, RNAs 3B and 5 represent a novel class of subgenomic RNAs from TAV that do not function as mRNAs. Possible functional roles for such a class of viral subgenomic RNAs are discussed.
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an interspecies hybrid rna virus is significantly more virulent than either parental virus
Proceedings of the National Academy of Sciences of the United States of America, 1996Co-Authors: Shouwei Ding, W X Li, Robert H SymonsAbstract:Abstract Cucumber mosaic Cucumovirus (CMV) infects a very wide range of plant species (>1000 species). We recently demonstrated that a previously undescribed gene (2b) encoded by RNA 2 of the tripartite RNA genome of CMV is required for systemic virus spread and disease induction in its hosts. Herein we report that when this CMV gene is replaced by its homologue from tomato aspermy Cucumovirus (TAV), the resultant hybrid virus is significantly more virulent, induces earlier onset of systemic symptoms, and accumulates to a higher level in seven host species from three families than either of the parents. Our results indicate that CMV and the TAV 2b protein interact synergistically despite the fact that no synergism occurs in double infections with the two parental viruses. To our knowledge, this is the first example of an interspecific hybrid made from plant or animal RNA viruses that is more efficient in systemic infection of a number of hosts than the naturally occurring parents. As CMV and the hybrid virus accumulated to a similar level in the infected tobacco protoplasts, the observed synergistic responses most likely resulted from an increased efficacy of the hybrid virus in systemic spread in host plants provided by the TAV 2b protein. The relevance of our finding to the application of pathogen-derived resistance is discussed.
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a novel naturally occurring hybrid gene encoded by a plant rna virus facilitates long distance virus movement
The EMBO Journal, 1995Co-Authors: Shouwei Ding, Wanxiang Li, Robert H SymonsAbstract:Abstract We recently identified a new Cucumovirus-specific gene (2b) which is encoded by RNA 2 of the cucumber mosaic Cucumovirus (CMV) tripartite RNA genome and whose coding sequence overlaps the C-terminal 69 codons of ORF 2a encoding the RNA polymerase protein. We have now found that although a CMV mutant lacking ORF 2b accumulated in the inoculated cotyledons of cucumber plants, it was unable to spread systemically, demonstrating involvement of 2b in long distance movement. The same mutant infected tobacco systemically with a much reduced virulence and delayed appearance of symptoms, indicating that 2b may contribute to long distance movement in this host. Deletion of the overlapping C-terminal part of ORF 2a did not change infectivity of the mutant in either host species, ruling out 2a mutation as the reason for the change of phenotype. Further infectivity studies with mutants containing partial deletions in ORF 2b further supported the conclusion that 2b encodes a host-specific long distance movement function. Sequence analysis revealed that 2b may represent a novel naturally occurring hybrid gene important to the evolutionary formation of the Cucumovirus group and that it could provide a genetic basis for the wide host range of these viruses.
Henryk Czosnek - One of the best experts on this subject based on the ideXlab platform.
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Expressing a whitefly GroEL protein in Nicotiana benthamiana plants confers tolerance to tomato yellow leaf curl virus and cucumber mosaic virus, but not to grapevine virus A or tobacco mosaic virus
Archives of Virology, 2009Co-Authors: Dagan Edelbaum, Rena Gorovits, Sonoko Sasaki, Masato Ikegami, Henryk CzosnekAbstract:Transgenesis offers many ways to obtain virus-resistant plants. However, in most cases resistance is against a single virus or viral strain. We have taken a novel approach based on the ability of a whitefly endosymbiotic GroEL to bind viruses belonging to several genera, in vivo and in vitro. We have expressed the GroEL gene in Nicotiana benthamiana plants, postulating that upon virus inoculation, GroEL will bind to virions, thereby interfering with pathogenesis. The transgenic plants were inoculated with the begomovirus tomato yellow leaf curl virus (TYLCV) and the Cucumovirus cucumber mosaic virus (CMV), both of which interacted with GroEL in vitro, and with the trichovirus grapevine virus A (GVA) and the tobamovirus tobacco mosaic virus (TMV), which did not. While the transgenic plants inoculated with TYLCV and CMV presented a high level of tolerance, those inoculated with GVA and TMV were susceptible. The amounts of virus in tolerant transgenic plants was lower by three orders of magnitude than those in non-transgenic plants; in comparison, the amounts of virus in susceptible transgenic plants were similar to those in non-transgenic plants. Leaf extracts of the tolerant plants contained GroEL-virus complexes. Hence, tolerance was correlated with trapping of viruses in planta. This study demonstrated that multiple resistances to viruses belonging to several different taxonomic genera could be achieved. Moreover, it might be hypothesized that plants expressing GroEL will be tolerant to those viruses that bind to GroEL in vitro, such as members of the genera Begomovirus, Cucumovirus, Ilarvirus, Luteovirus, and Tospovirus.
Katalin Salánki - One of the best experts on this subject based on the ideXlab platform.
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Molecular Modeling for Better Understanding of Cucumovirus Pathology.
Advances in virus research, 2018Co-Authors: Katalin Salánki, Ákos Gellért, Katalin Nemes, Zoltán Divéki, Ervin BalázsAbstract:Cucumber mosaic virus (CMV) is a small RNA virus capable of infecting a wide variety of plant species. The high economic losses due to the CMV infection made this virus a relevant subject of scientific studies, which were further facilitated by the small size of the viral genome. Hence, CMV also became a model organism to investigate the molecular mechanism of pathogenesis. All viral functions are dependent on intra- and intermolecular interactions between nucleic acids and proteins of the virus and the host. This review summarizes the recent data on molecular determinants of such interactions. A particular emphasis is given to the results obtained by utilizing molecular-based planning and modeling techniques.
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Nucleotide sequence analysis of peanut stunt virus Rp strain suggests the role of homologous recombination in Cucumovirus evolution
Archives of Virology, 2008Co-Authors: László Kiss, Ervin Balázs, Endre Sebestyén, Emese László, Pál Salamon, Katalin SalánkiAbstract:The complete nucleotide (nt) sequence of peanut stunt virus Robinia strain (PSV-Rp) was determined and compared to other PSV strains and to representatives of the genus Cucumovirus. Nt sequence comparison showed 74.1–84.6% identity with the known PSV strains. Phylogenetic analysis revealed the different origin of the two genes encoded by RNA3. While the 3a gene clustered with PSV-W, the coat protein gene clustered with PSV-Mi. Recombination breakpoint analysis revealed two recombination points on RNA3. Based on these results, the establishment of a fourth PSV subgroup is proposed. This work revealed that homologous recombination occurred during the evolution of PSV.
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Homology modelling and protein structure based functional analysis of five Cucumovirus coat proteins.
Journal of molecular graphics & modelling, 2005Co-Authors: Ákos Gellért, Katalin Salánki, Gábor Náray-szabó, Ervin BalázsAbstract:Abstract Coat proteins (CP) of five Cucumovirus isolates, Cucumber mosaic virus (CMV) strains R, M and Trk7, Tomato aspermy virus (TAV) strain P and Peanut stunt virus (PSV) strain Er, were constructed by homology modelling. The X-ray structure of the Fny-CMV CP subunit B was used as a template. Models of Cucumovirus CPs were built by the MODELLER program. Model refinements were carried out using the Kollman molecular mechanical force field. Models were analyzed by the PROCHECK programs. Electrostatic potential calculations were applied to all models and functional site search was performed with the PROSITE software, a web based tool for searching biologically significant sites. Symptom determinants published up to the present were compared with the PROSITE hits in the light of 3D models and electrostatic information. In all cases, we analyzed the effect of mutations on the structure, electrostatic potential patterns and function of CPs, respectively. We found that high flexibility of the βE–αEF loop starting with the residue 129 is required, but it is not sufficient for the symptom appearance. Furthermore, phosphorylation of the CP is prospective to be important in the host response mechanism. All analyzed mutations were related to the modifications of the predicted phosphorylation sites. Based on our conclusions we predicted the infectivity of the examined viruses.
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behavior of Cucumovirus pseudorecombinant and recombinant strains in solanaceous hosts
1997Co-Authors: Mireille Jacquemond, Katalin Salánki, Ervin Balázs, Isabelle Carrere, Mark TepferAbstract:Pseudorecombinant and chimeric recombinant strains have been created between two strains of cucumber mosaic virus (I17F-CMV and R-CMV) or between R-CMV and tomato aspermy virus (P-TAV), and their biological properties have been assessed on certain solanaceous hosts. Results involving the two CMV strains suggest that the different hosts fall into two main groups. The first corresponds to hosts for which the nature or the gravity of the symptoms is mainly determined by RNAs 1 and 2. The second group is composed of hosts for which symptomatology is mainly governed by RNA 3. In these cases, it is the 3′ part of the molecule, bearing the coat protein (CP) gene, which is primarily involved. One chimeric recombinant CMV strain has distinctive properties, since it cumulates the severe symptoms induced by both parental strains in Nicotiana glutinosa. Pseudorecombinants and recombinants created between R-CMV and P-TAV confirmed the importance of the 3′ part of RNA 3 in determining symptomatology in this host. Unexpected results were observed with one chimeric recombinant, which proved unable to infect tobacco, although it can replicate in tobacco cells. The pseudorecombinant strain composed of P-TAV RNAs 1 and 2 and RNA 3 from R-CMV induced considerably aggravated symptoms on Nicotiana benthamiana. This property is not related to a difference in replication efficiency.
Ervin Balázs - One of the best experts on this subject based on the ideXlab platform.
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Molecular Modeling for Better Understanding of Cucumovirus Pathology.
Advances in virus research, 2018Co-Authors: Katalin Salánki, Ákos Gellért, Katalin Nemes, Zoltán Divéki, Ervin BalázsAbstract:Cucumber mosaic virus (CMV) is a small RNA virus capable of infecting a wide variety of plant species. The high economic losses due to the CMV infection made this virus a relevant subject of scientific studies, which were further facilitated by the small size of the viral genome. Hence, CMV also became a model organism to investigate the molecular mechanism of pathogenesis. All viral functions are dependent on intra- and intermolecular interactions between nucleic acids and proteins of the virus and the host. This review summarizes the recent data on molecular determinants of such interactions. A particular emphasis is given to the results obtained by utilizing molecular-based planning and modeling techniques.
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Nucleotide sequence analysis of peanut stunt virus Rp strain suggests the role of homologous recombination in Cucumovirus evolution
Archives of Virology, 2008Co-Authors: László Kiss, Ervin Balázs, Endre Sebestyén, Emese László, Pál Salamon, Katalin SalánkiAbstract:The complete nucleotide (nt) sequence of peanut stunt virus Robinia strain (PSV-Rp) was determined and compared to other PSV strains and to representatives of the genus Cucumovirus. Nt sequence comparison showed 74.1–84.6% identity with the known PSV strains. Phylogenetic analysis revealed the different origin of the two genes encoded by RNA3. While the 3a gene clustered with PSV-W, the coat protein gene clustered with PSV-Mi. Recombination breakpoint analysis revealed two recombination points on RNA3. Based on these results, the establishment of a fourth PSV subgroup is proposed. This work revealed that homologous recombination occurred during the evolution of PSV.
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Homology modelling and protein structure based functional analysis of five Cucumovirus coat proteins.
Journal of molecular graphics & modelling, 2005Co-Authors: Ákos Gellért, Katalin Salánki, Gábor Náray-szabó, Ervin BalázsAbstract:Abstract Coat proteins (CP) of five Cucumovirus isolates, Cucumber mosaic virus (CMV) strains R, M and Trk7, Tomato aspermy virus (TAV) strain P and Peanut stunt virus (PSV) strain Er, were constructed by homology modelling. The X-ray structure of the Fny-CMV CP subunit B was used as a template. Models of Cucumovirus CPs were built by the MODELLER program. Model refinements were carried out using the Kollman molecular mechanical force field. Models were analyzed by the PROCHECK programs. Electrostatic potential calculations were applied to all models and functional site search was performed with the PROSITE software, a web based tool for searching biologically significant sites. Symptom determinants published up to the present were compared with the PROSITE hits in the light of 3D models and electrostatic information. In all cases, we analyzed the effect of mutations on the structure, electrostatic potential patterns and function of CPs, respectively. We found that high flexibility of the βE–αEF loop starting with the residue 129 is required, but it is not sufficient for the symptom appearance. Furthermore, phosphorylation of the CP is prospective to be important in the host response mechanism. All analyzed mutations were related to the modifications of the predicted phosphorylation sites. Based on our conclusions we predicted the infectivity of the examined viruses.
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behavior of Cucumovirus pseudorecombinant and recombinant strains in solanaceous hosts
1997Co-Authors: Mireille Jacquemond, Katalin Salánki, Ervin Balázs, Isabelle Carrere, Mark TepferAbstract:Pseudorecombinant and chimeric recombinant strains have been created between two strains of cucumber mosaic virus (I17F-CMV and R-CMV) or between R-CMV and tomato aspermy virus (P-TAV), and their biological properties have been assessed on certain solanaceous hosts. Results involving the two CMV strains suggest that the different hosts fall into two main groups. The first corresponds to hosts for which the nature or the gravity of the symptoms is mainly determined by RNAs 1 and 2. The second group is composed of hosts for which symptomatology is mainly governed by RNA 3. In these cases, it is the 3′ part of the molecule, bearing the coat protein (CP) gene, which is primarily involved. One chimeric recombinant CMV strain has distinctive properties, since it cumulates the severe symptoms induced by both parental strains in Nicotiana glutinosa. Pseudorecombinants and recombinants created between R-CMV and P-TAV confirmed the importance of the 3′ part of RNA 3 in determining symptomatology in this host. Unexpected results were observed with one chimeric recombinant, which proved unable to infect tobacco, although it can replicate in tobacco cells. The pseudorecombinant strain composed of P-TAV RNAs 1 and 2 and RNA 3 from R-CMV induced considerably aggravated symptoms on Nicotiana benthamiana. This property is not related to a difference in replication efficiency.