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Stephan Winter - One of the best experts on this subject based on the ideXlab platform.
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localization of cassava brown streak virus in nicotiana rustica and cassava manihot esculenta crantz using rnascope in situ hybridization
Virology Journal, 2018Co-Authors: Esperance Munganyinka, Paolo Margaria, Samar Sheat, E M Ateka, Fred Tairo, Joseph Ndunguru, Stephan WinterAbstract:Background Cassava brown streak disease (CBSD) has a viral aetiology and is caused by viruses belonging to the genus Ipomovirus (family Potyviridae), Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Molecular and serological methods are available for detection, discrimination and quantification of cassava brown streak viruses (CBSVs) in infected plants. However, precise determination of the viral RNA localization in infected host tissues is still not possible pending appropriate methods.
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Localization of cassava brown streak virus in Nicotiana rustica and cassava Manihot esculenta (Crantz) using RNAscope® in situ hybridization
BMC, 2018Co-Authors: Esperance Munganyinka, Paolo Margaria, Samar Sheat, E M Ateka, Fred Tairo, Joseph Ndunguru, Stephan WinterAbstract:Abstract Background Cassava brown streak disease (CBSD) has a viral aetiology and is caused by viruses belonging to the genus Ipomovirus (family Potyviridae), Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Molecular and serological methods are available for detection, discrimination and quantification of cassava brown streak viruses (CBSVs) in infected plants. However, precise determination of the viral RNA localization in infected host tissues is still not possible pending appropriate methods. Results We have developed an in situ hybridization (ISH) assay based on RNAscope® technology that allows the sensitive detection and localization of CBSV RNA in plant tissues. The method was initially developed in the experimental host Nicotiana rustica and was then further adapted to cassava. Highly sensitive and specific detection of CBSV RNA was achieved without background and hybridization signals in sections prepared from non-infected tissues. The tissue tropism of CBSV RNAs appeared different between N. rustica and cassava. Conclusions This study provides a robust method for CBSV detection in the experimental host and in cassava. The protocol will be used to study CBSV tropism in various cassava genotypes, as well as CBSVs/cassava interactions in single and mixed infections
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analysis of the complete genome sequence of euphorbia ringspot virus an atypical member of the genus potyvirus
Archives of Virology, 2017Co-Authors: Dennis Knierim, Wulf Menzel, Stephan WinterAbstract:The complete genome sequence of an isolate of euphorbia ringspot virus (EuRSV) was determined by deep sequencing and rapid amplification of cDNA ends (RACE) RT-PCR. It has an RNA genome of 10,154 nucleotides in size, excluding the poly(A) tail, and encodes a polyprotein of 3265 amino acids. Phylogenetic analysis from this study supports the earlier taxonomic assignment to the genus Potyvirus; however, a gene encoding the HAM1h protein, inserted between NIb and CP of the EuRSV genome, which was previously only observed for cassava brown streak virus and Ugandan cassava brown streak virus of the genus Ipomovirus, is an unusual feature of this potyvirus, which otherwise has typical potyvirus genome features.
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Variability in P1 gene redefines phylogenetic relationships among cassava brown streak viruses
'Springer Science and Business Media LLC', 2017Co-Authors: Willard Mbewe, Samar Sheat, Fred Tairo, Joseph Ndunguru, Peter Sseruwagi, Siobain Duffy, Ssetumba Mukasa, Ibrahim Benesi, Marianne Koerbler, Stephan WinterAbstract:Abstract Background Cassava brown streak disease is emerging as the most important viral disease of cassava in Africa, and is consequently a threat to food security. Two distinct species of the genus Ipomovirus (family Potyviridae) cause the disease: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). To understand the evolutionary relationships among the viruses, 64 nucleotide sequences from the variable P1 gene from major cassava producing areas of east and central-southern Africa were determined. Methods We sequenced an amplicon of the P1 region of 31 isolates from Malawi and Tanzania. In addition to these, 33 previously reported sequences of virus isolates from Uganda, Kenya, Tanzania, Malawi and Mozambique were added to the analysis. Results Phylogenetic analyses revealed three major P1 clades of Cassava brown streak viruses (CBSVs): in addition to a clade of most CBSV and a clade containing all UCBSV, a novel, intermediate clade of CBSV isolates which has been tentatively called CBSV-Tanzania (CBSV-TZ). Virus isolates of the distinctive CBSV-TZ had nucleotide identities as low as 63.2 and 63.7% with other members of CBSV and UCBSV respectively. Conclusions Grouping of P1 gene sequences indicated for distinct sub-populations of CBSV, but not UCBSV. Representatives of all three clades were found in both Tanzania and Malawi
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analysis of the tomato mild mottle virus genome indicates that it is the most divergent member of the genus Ipomovirus family potyviridae
Archives of Virology, 2012Co-Authors: Adane Abraham, Wulf Menzel, Josef H Vetten, Stephan WinterAbstract:The complete genome of a tomato mild mottle virus (ToMMV) isolate was analysed, and some biological features were characterized. The ssRNA genome of ToMMV from Ethiopia encompasses 9283 nucleotides (excluding the 3′ poly(A) tail) and encodes a polyprotein of 3011 amino acids. Phylogenetic and pairwise comparisons with other members of the family Potyviridae revealed that ToMMV is the most divergent member of the genus Ipomovirus, with a genome organization similar to that of members of the species Sweet potato mild mottle virus, the type species of the genus. In contrast to earlier reports, ToMMV isolates from Yemen and Ethiopia were not transmitted by the aphid Myzus persicae, but they were transmitted very erratically by the whitefly Bemisia tabaci. A comparison of the 3′-proximal sequences of different isolates provided evidence for geographically associated genetic variation.
Deusdedith R Mbanzibwa - One of the best experts on this subject based on the ideXlab platform.
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evolution of cassava brown streak disease associated viruses
Journal of General Virology, 2011Co-Authors: Deusdedith R Mbanzibwa, Yanping Tian, Arthur K Tugume, Basavaprabhu L Patil, M M Abarshi, Jitender S Yadav, Basavaraj Bagewadi, Titus AlicaiAbstract:Cassava brown streak disease (CBSD) has occurred in the Indian Ocean coastal lowlands and some areas of Malawi in East Africa for decades, and makes the storage roots of cassava unsuitable for consumption. CBSD is associated with Cassava brown streak virus (CBSV) and the recently described Ugandan cassava brown streak virus (UCBSV) [picorna-like (+)ssRNA viruses; genus Ipomovirus; family Potyviridae]. This study reports the first comprehensive analysis on how evolution is shaping the populations of CBSV and UCBSV. The complete genomes of CBSV and UCBSV (four and eight isolates, respectively) were 69.0–70.3 and 73.6–74.4% identical at the nucleotide and polyprotein amino acid sequence levels, respectively. They contained predictable sites of homologous recombination, mostly in the 39-proximal part (NIb-HAM1h-CP-39-UTR) of the genome, but no evidence of recombination between the two viruses was found. The CP-encoding sequences of 22 and 45 isolates of CBSV and UCBSV analysed, respectively, were mainly under purifying selection; however, several sites in the central part of CBSV CP were subjected to positive selection. HAM1h (putative nucleoside triphosphate pyrophosphatase) was the least similar protein between CBSV and UCBSV (aa identity approx. 55 %). Both termini of HAM1h contained sites under positive selection in UCBSV. The data imply an on-going but somewhat different evolution of CBSV and UCBSV, which is congruent with the recent widespread outbreak of UCBSV in cassava crops in the highland areas (.1000 m above sea level) of East Africa where CBSD has not caused significant problems in the past.
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simultaneous virus specific detection of the two cassava brown streak associated viruses by rt pcr reveals wide distribution in east africa mixed infections and infections in manihot glaziovii
Journal of Virological Methods, 2011Co-Authors: Deusdedith R Mbanzibwa, Yanping Tian, S B Mukasa, Fred Tairo, Arthur K Tugume, S Kyamanywa, A Kullaya, Jari P. T. ValkonenAbstract:The expanding cassava brown streak disease (CBSD) epidemic in East Africa is caused by two Ipomoviruses (genus Ipomovirus; Potyviridae), namely, Cassava brown streak virus (CBSV), and Ugandan cassava brown streak virus (UCBSV) that was described recently. A reverse transcription polymerase chain reaction (RT-PCR) based diagnostic method was developed in this study for simultaneous virus-specific detection of the two viruses. Results showed that CBSV and UCBSV are distributed widely in the highlands (>1000 m above the sea level) of the Lake Victoria zone in Uganda and Tanzania and also in the Indian Ocean costal lowlands of Tanzania. Isolates of UCBSV from the Lake Victoria zone were placed to two phylogenetic clusters in accordance with their origin in Uganda or Tanzania, respectively. Mixed infections with CBSV and UCBSV were detected in many cassava plants in the areas surveyed. CBSV was also detected in the perennial species Manihot glaziovii (DNA-barcoded in this study) in Tanzania, which revealed the first virus reservoir other than cassava. The method for detection of CBSV and UCBSV described in this study has important applications for plant quarantine, resistance breeding of cassava, and studies on epidemiology and control of CBSD in East Africa.
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cassava brown streak virus potyviridae encodes a putative maf ham1 pyrophosphatase implicated in reduction of mutations and a p1 proteinase that suppresses rna silencing but contains no hc pro
Journal of Virology, 2009Co-Authors: Yanping Tian, Deusdedith R Mbanzibwa, S B Mukasa, Jari P. T. ValkonenAbstract:The complete positive-sense single-stranded RNA genome of Cassava brown streak virus (CBSV; genus Ipomovirus ; Potyviridae ) was found to consist of 9,069 nucleotides and predicted to produce a polyprotein of 2,902 amino acids. It was lacking helper-component proteinase but contained a single P1 serine proteinase that strongly suppressed RNA silencing. Besides the exceptional structure of the 5′-proximal part of the genome, CBSV also contained a Maf/HAM1-like sequence (678 nucleotides, 226 amino acids) recombined between the replicase and coat protein domains in the 3′-proximal part of the genome, which is highly conserved in Potyviridae . HAM1 was flanked by consensus proteolytic cleavage sites for Ipomovirus NIaPro cysteine proteinase. Homology of CBSV HAM1 with cellular Maf/HAM1 pyrophosphatases suggests that it may intercept noncanonical nucleoside triphosphates to reduce mutagenesis of viral RNA.
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genetically distinct strains of cassava brown streak virus in the lake victoria basin and the indian ocean coastal area of east africa
Archives of Virology, 2009Co-Authors: Deusdedith R Mbanzibwa, Yanping Tian, S B Mukasa, Fred Tairo, Arthur K Tugume, S Kyamanywa, A Kullaya, Jari P. T. ValkonenAbstract:Six isolates of Cassava brown streak virus (CBSV, genus Ipomovirus; Potyviridae) from the Lake Victoria basin in Uganda and Tanzania were characterized. Virus particles were 650 nm long. The complete coat protein (CP)-encoding sequences (1,101 nucleotides, nt) were 90.7–99.5 and 93.7–99.5% identical at the nt and amino acid (aa) levels, respectively. The 3′ untranslated region was 225, 226 or 227 nt long. These eight isolates were only 75.8–77.5% (nt) and 87.0–89.9% (aa) identical when compared to the partial CP sequences (714 nt) of six CBSV isolates characterized previously from the costal lowlands of Tanzania and Mozambique. Hence, two genetically different and geographically separated populations of CSBV exist in East Africa.
Jari P. T. Valkonen - One of the best experts on this subject based on the ideXlab platform.
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simultaneous virus specific detection of the two cassava brown streak associated viruses by rt pcr reveals wide distribution in east africa mixed infections and infections in manihot glaziovii
Journal of Virological Methods, 2011Co-Authors: Deusdedith R Mbanzibwa, Yanping Tian, S B Mukasa, Fred Tairo, Arthur K Tugume, S Kyamanywa, A Kullaya, Jari P. T. ValkonenAbstract:The expanding cassava brown streak disease (CBSD) epidemic in East Africa is caused by two Ipomoviruses (genus Ipomovirus; Potyviridae), namely, Cassava brown streak virus (CBSV), and Ugandan cassava brown streak virus (UCBSV) that was described recently. A reverse transcription polymerase chain reaction (RT-PCR) based diagnostic method was developed in this study for simultaneous virus-specific detection of the two viruses. Results showed that CBSV and UCBSV are distributed widely in the highlands (>1000 m above the sea level) of the Lake Victoria zone in Uganda and Tanzania and also in the Indian Ocean costal lowlands of Tanzania. Isolates of UCBSV from the Lake Victoria zone were placed to two phylogenetic clusters in accordance with their origin in Uganda or Tanzania, respectively. Mixed infections with CBSV and UCBSV were detected in many cassava plants in the areas surveyed. CBSV was also detected in the perennial species Manihot glaziovii (DNA-barcoded in this study) in Tanzania, which revealed the first virus reservoir other than cassava. The method for detection of CBSV and UCBSV described in this study has important applications for plant quarantine, resistance breeding of cassava, and studies on epidemiology and control of CBSD in East Africa.
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recombination and selection pressure in the Ipomovirus sweet potato mild mottle virus potyviridae in wild species and cultivated sweetpotato in the centre of evolution in east africa
Journal of General Virology, 2010Co-Authors: Arthur K Tugume, S B Mukasa, Nisse Kalkkinen, Jari P. T. ValkonenAbstract:Sweet potato mild mottle virus (SPMMV) is the type member of the genus Ipomovirus (family Potyviridae). SPMMV occurs in cultivated sweetpotatoes (Ipomoea batatas Lam.; Convolvulaceae) in East Africa, but its natural wild hosts are unknown. In this study, SPMMV was detected in 283 (9.8 %) of the 2864 wild plants (family Convolvulaceae) sampled from different agro-ecological zones of Uganda. The infected plants belonged to 21 species that were previously not known to be natural hosts of SPMMV. The size of the SPMMV coat protein (CP) was determined by Western blot analysis, N-terminal protein sequencing and peptide mass fingerprinting. Data implicated a proteolytic cleavage site, VYVEPH/A, at the NIb/CP junction, resulting in a CP of approximately 35 kDa. Nearly complete sequences of 13 SPMMV isolates were characterized. Phylogenetic analysis of non-recombinant CP-encoding sequences placed five isolates from wild species sampled in the central zone of Uganda into a separate cluster. Recombination events were detected in the 5'- and 3'-proximal parts of the genome, providing novel evidence of recombination in the genus Ipomovirus. Thirteen amino acids in the N terminus of the P1 protein were under positive selection, whereas purifying selection was implicated for the HC-Pro-, P3-, 6K1- and CP-encoding regions. These data, supported by previous studies on Ipomoviruses, provide indications of an evolutionary process in which the P1 proteinase responds to the needs of adaptation.
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cassava brown streak virus potyviridae encodes a putative maf ham1 pyrophosphatase implicated in reduction of mutations and a p1 proteinase that suppresses rna silencing but contains no hc pro
Journal of Virology, 2009Co-Authors: Yanping Tian, Deusdedith R Mbanzibwa, S B Mukasa, Jari P. T. ValkonenAbstract:The complete positive-sense single-stranded RNA genome of Cassava brown streak virus (CBSV; genus Ipomovirus ; Potyviridae ) was found to consist of 9,069 nucleotides and predicted to produce a polyprotein of 2,902 amino acids. It was lacking helper-component proteinase but contained a single P1 serine proteinase that strongly suppressed RNA silencing. Besides the exceptional structure of the 5′-proximal part of the genome, CBSV also contained a Maf/HAM1-like sequence (678 nucleotides, 226 amino acids) recombined between the replicase and coat protein domains in the 3′-proximal part of the genome, which is highly conserved in Potyviridae . HAM1 was flanked by consensus proteolytic cleavage sites for Ipomovirus NIaPro cysteine proteinase. Homology of CBSV HAM1 with cellular Maf/HAM1 pyrophosphatases suggests that it may intercept noncanonical nucleoside triphosphates to reduce mutagenesis of viral RNA.
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genetically distinct strains of cassava brown streak virus in the lake victoria basin and the indian ocean coastal area of east africa
Archives of Virology, 2009Co-Authors: Deusdedith R Mbanzibwa, Yanping Tian, S B Mukasa, Fred Tairo, Arthur K Tugume, S Kyamanywa, A Kullaya, Jari P. T. ValkonenAbstract:Six isolates of Cassava brown streak virus (CBSV, genus Ipomovirus; Potyviridae) from the Lake Victoria basin in Uganda and Tanzania were characterized. Virus particles were 650 nm long. The complete coat protein (CP)-encoding sequences (1,101 nucleotides, nt) were 90.7–99.5 and 93.7–99.5% identical at the nt and amino acid (aa) levels, respectively. The 3′ untranslated region was 225, 226 or 227 nt long. These eight isolates were only 75.8–77.5% (nt) and 87.0–89.9% (aa) identical when compared to the partial CP sequences (714 nt) of six CBSV isolates characterized previously from the costal lowlands of Tanzania and Mozambique. Hence, two genetically different and geographically separated populations of CSBV exist in East Africa.
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interactions between a crinivirus an Ipomovirus and a potyvirus in coinfected sweetpotato plants
Plant Pathology, 2006Co-Authors: Jari P. T. Valkonen, S B Mukasa, P R RubaihayoAbstract:Novel and severe symptoms of chlorosis, rugosity, leaf strapping and dark green islands, designated as sweetpotato severe mosaic disease (SPSMD), were caused by dual infection of Sweet potato mild mottle virus (SPMMV; Ipomovirus ) and Sweet potato chlorotic stunt virus (SPCSV; Crinivirus ) in three East African sweetpotato cultivars (Tanzania, Dimbuka and New Kawogo). The storage root yield was reduced by ∼ 80%, as compared with healthy plants under screenhouse conditions in Uganda. Plants infected with SPMMV or SPCSV alone showed nonsignificant or 50% yield reduction, respectively. SPCSV reduced resistance to SPMMV in sweetpotato, similar to the situation with resistance to Sweet potato feathery mottle virus (SPFMV; Potyvirus ) that breaks down following infection with SPCSV, followed by development of sweet potato virus disease (SPVD). In single virus infections with SPMMV and SPFMV or their coinfection, cvs Tanzania and Dimbuka were initially systemically infected, displayed symptoms and contained readily detectable virus titres, but new leaves were symptomless with very low virus titres, indicating recovery from disease. In contrast, cv. New Kawogo remained symptomless and contained low SPMMV and SPFMV titres following graft inoculation. These moderate and high levels of resistance to SPMMV and SPFMV, respectively, were lost and cultivars succumbed to a severe disease following coinfection with SPCSV. The synergistic interactions increased titres of SPMMV and SPFMV RNA by ∼ 1000fold as quantified by real-time PCR, whereas SPCSV titres were reduced twofold, indicating an antagonistic interaction. Coinfection with SPMMV and SPFMV caused no detectable changes in virus titres or symptom severity.
Arthur K Tugume - One of the best experts on this subject based on the ideXlab platform.
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evolution of cassava brown streak disease associated viruses
Journal of General Virology, 2011Co-Authors: Deusdedith R Mbanzibwa, Yanping Tian, Arthur K Tugume, Basavaprabhu L Patil, M M Abarshi, Jitender S Yadav, Basavaraj Bagewadi, Titus AlicaiAbstract:Cassava brown streak disease (CBSD) has occurred in the Indian Ocean coastal lowlands and some areas of Malawi in East Africa for decades, and makes the storage roots of cassava unsuitable for consumption. CBSD is associated with Cassava brown streak virus (CBSV) and the recently described Ugandan cassava brown streak virus (UCBSV) [picorna-like (+)ssRNA viruses; genus Ipomovirus; family Potyviridae]. This study reports the first comprehensive analysis on how evolution is shaping the populations of CBSV and UCBSV. The complete genomes of CBSV and UCBSV (four and eight isolates, respectively) were 69.0–70.3 and 73.6–74.4% identical at the nucleotide and polyprotein amino acid sequence levels, respectively. They contained predictable sites of homologous recombination, mostly in the 39-proximal part (NIb-HAM1h-CP-39-UTR) of the genome, but no evidence of recombination between the two viruses was found. The CP-encoding sequences of 22 and 45 isolates of CBSV and UCBSV analysed, respectively, were mainly under purifying selection; however, several sites in the central part of CBSV CP were subjected to positive selection. HAM1h (putative nucleoside triphosphate pyrophosphatase) was the least similar protein between CBSV and UCBSV (aa identity approx. 55 %). Both termini of HAM1h contained sites under positive selection in UCBSV. The data imply an on-going but somewhat different evolution of CBSV and UCBSV, which is congruent with the recent widespread outbreak of UCBSV in cassava crops in the highland areas (.1000 m above sea level) of East Africa where CBSD has not caused significant problems in the past.
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simultaneous virus specific detection of the two cassava brown streak associated viruses by rt pcr reveals wide distribution in east africa mixed infections and infections in manihot glaziovii
Journal of Virological Methods, 2011Co-Authors: Deusdedith R Mbanzibwa, Yanping Tian, S B Mukasa, Fred Tairo, Arthur K Tugume, S Kyamanywa, A Kullaya, Jari P. T. ValkonenAbstract:The expanding cassava brown streak disease (CBSD) epidemic in East Africa is caused by two Ipomoviruses (genus Ipomovirus; Potyviridae), namely, Cassava brown streak virus (CBSV), and Ugandan cassava brown streak virus (UCBSV) that was described recently. A reverse transcription polymerase chain reaction (RT-PCR) based diagnostic method was developed in this study for simultaneous virus-specific detection of the two viruses. Results showed that CBSV and UCBSV are distributed widely in the highlands (>1000 m above the sea level) of the Lake Victoria zone in Uganda and Tanzania and also in the Indian Ocean costal lowlands of Tanzania. Isolates of UCBSV from the Lake Victoria zone were placed to two phylogenetic clusters in accordance with their origin in Uganda or Tanzania, respectively. Mixed infections with CBSV and UCBSV were detected in many cassava plants in the areas surveyed. CBSV was also detected in the perennial species Manihot glaziovii (DNA-barcoded in this study) in Tanzania, which revealed the first virus reservoir other than cassava. The method for detection of CBSV and UCBSV described in this study has important applications for plant quarantine, resistance breeding of cassava, and studies on epidemiology and control of CBSD in East Africa.
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recombination and selection pressure in the Ipomovirus sweet potato mild mottle virus potyviridae in wild species and cultivated sweetpotato in the centre of evolution in east africa
Journal of General Virology, 2010Co-Authors: Arthur K Tugume, S B Mukasa, Nisse Kalkkinen, Jari P. T. ValkonenAbstract:Sweet potato mild mottle virus (SPMMV) is the type member of the genus Ipomovirus (family Potyviridae). SPMMV occurs in cultivated sweetpotatoes (Ipomoea batatas Lam.; Convolvulaceae) in East Africa, but its natural wild hosts are unknown. In this study, SPMMV was detected in 283 (9.8 %) of the 2864 wild plants (family Convolvulaceae) sampled from different agro-ecological zones of Uganda. The infected plants belonged to 21 species that were previously not known to be natural hosts of SPMMV. The size of the SPMMV coat protein (CP) was determined by Western blot analysis, N-terminal protein sequencing and peptide mass fingerprinting. Data implicated a proteolytic cleavage site, VYVEPH/A, at the NIb/CP junction, resulting in a CP of approximately 35 kDa. Nearly complete sequences of 13 SPMMV isolates were characterized. Phylogenetic analysis of non-recombinant CP-encoding sequences placed five isolates from wild species sampled in the central zone of Uganda into a separate cluster. Recombination events were detected in the 5'- and 3'-proximal parts of the genome, providing novel evidence of recombination in the genus Ipomovirus. Thirteen amino acids in the N terminus of the P1 protein were under positive selection, whereas purifying selection was implicated for the HC-Pro-, P3-, 6K1- and CP-encoding regions. These data, supported by previous studies on Ipomoviruses, provide indications of an evolutionary process in which the P1 proteinase responds to the needs of adaptation.
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genetically distinct strains of cassava brown streak virus in the lake victoria basin and the indian ocean coastal area of east africa
Archives of Virology, 2009Co-Authors: Deusdedith R Mbanzibwa, Yanping Tian, S B Mukasa, Fred Tairo, Arthur K Tugume, S Kyamanywa, A Kullaya, Jari P. T. ValkonenAbstract:Six isolates of Cassava brown streak virus (CBSV, genus Ipomovirus; Potyviridae) from the Lake Victoria basin in Uganda and Tanzania were characterized. Virus particles were 650 nm long. The complete coat protein (CP)-encoding sequences (1,101 nucleotides, nt) were 90.7–99.5 and 93.7–99.5% identical at the nt and amino acid (aa) levels, respectively. The 3′ untranslated region was 225, 226 or 227 nt long. These eight isolates were only 75.8–77.5% (nt) and 87.0–89.9% (aa) identical when compared to the partial CP sequences (714 nt) of six CBSV isolates characterized previously from the costal lowlands of Tanzania and Mozambique. Hence, two genetically different and geographically separated populations of CSBV exist in East Africa.
Hervé Lecoq - One of the best experts on this subject based on the ideXlab platform.
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Characterization of a new cucurbit-infecting Ipomovirus from Sudan
Archives of Virology, 2016Co-Authors: Cecile Desbiez, Eric Verdin, Mark Tepfer, Catherine Wipf-scheibel, Pauline Millot, Gasim Dafalla, Hervé LecoqAbstract:Two members of the genus Ipomovirus (family Potyviridae) are known to infect cucurbits: cucumber vein yellowing virus (CVYV), which is emerging throughout the Mediterranean Basin, and squash vein yellowing virus (SqVYV), which has been described in America and the Caribbean Basin, and more recently in Israel. In this work, an Ipomovirus different from CVYV and SqVYV, tentatively named coccinia mottle virus (CocMoV), was detected in a sample of the cucurbit Coccinia grandis collected in central Sudan in 2012. Sequence identity in nt was 68 % with CVYV, 59-60 % with SqVYV, cassava brown streak virus and Ugandan cassava brown streak virus, and less than 50 % with other members of the family Potyviridae. Preliminary biological and epidemiological studies indicate that CocMoV has a narrow natural host range and a low prevalence.
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Occurrence of cucurbit yellow stunting disorder virus and cucumber vein yellowing virus in Tunisia
Journal of Plant Pathology, 2007Co-Authors: S. Yakoubi, Cecile Desbiez, Catherine Wipf-scheibel, H. Fakhfakh, M. Marrakchi, Hervé LecoqAbstract:During surveys carried out in June and October 2005 and August 2006 for assessing the occurrence of cucurbit- infecting viruses in Tunisia, samples of squash, melon and snake cucumber showing virus-like symptoms were collected from the major cucurbit-growing areas. Besides mosaic-inducing viruses, DAS-ELISA and RT-PCR tests showed the presence of yellows-inducing viruses: Cucurbit aphid-borne yellows virus (CABYV, Polerovirus), Cucurbit yellow stunting disorder virus (CYSDV, Crinivirus) and Cucumber vein yellowing virus (CVYV, Ipomovirus). While CABYV, a virus previously reported from Tunisia, was detected throughout the country, CYSDV and CVYV, reported here for the first time, were found only in the Sahel and the Southern part of the country. The identification of CYSDV and CVYV was confirmed by immunosorbent electron microscopy. Phylogenetic analysis done on parts of the CP gene sequence showed that Tunisian CYSDV isolates have high sequence identity (99-100%) with isolates that have recently emerged in the Middle East, Southern Europe and the United States. In contrast, CVYV isolates from Tunisia are more divergent (96.6%) from Middle East isolates and are only distantly related (94.5-95%) to isolates which recently emerged in Spain, Portugal and France.
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Cytological and molecular evidence that the whitefly-transmitted Cucumber vein yellowing virus is a tentative member of the family Potyviridae
Journal of General Virology, 2000Co-Authors: Hervé Lecoq, Cecile Desbiez, Brigitte Delecolle, S. Cohen, A. MansourAbstract:Cucumber vein yellowing virus (CVYV) is widespread in cucurbits in the Middle East. CVYV has filamentous particles and is transmitted by Bemisia tabaci by the semi-persistent mode. It has not yet been assigned to a specific genus or family. Ultramicroscopic observations revealed numerous cylindrical cytoplasmic inclusions in melon and cucumber cells infected by CVYV isolates from Israel and Jordan. Depending on the section orientation, the inclusions appeared as pinwheels or as bundles. In addition, a 1.9 kb DNA fragment was amplified by RT-PCR from CVYV-infected plant extracts using primers designed to detect all potyvirids. Sequence comparisons with the amplified fragment indicated that CVYV is more closely related to Sweet potato mild mottle virus than to any other virus in the family Potyviridae. These results suggest that CVYV can be considered as a tentative new member of the genus Ipomovirus, family Potyviridae.
