Publications

a nanovirus-like dna component associated with yellow vein disease of ageratum conyzoides: evidence for interfamilial recombination between plant dna viruses.	yellow vein disease of ageratum conyzoides, a weed species that is widely distributed throughout asia, has been attributed to infection by the geminivirus ageratum yellow vein virus (ayvv). in addition to a single ayvv genomic component (dna a), we have previously demonstrated that infected plants contain chimeric defective viral components, comprising dna a and nongeminiviral sequences, that act as defective interfering dnas. a database search has revealed that the nongeminiviral sequences of o ...	1999	10544139
recombination between viral dna and the transgenic coat protein gene of african cassava mosaic geminivirus.	nicotiana benthamiana was transformed with three different constructs (pcra1, pcra2 and pjc1) containing the coat protein coding sequence of african cassava mosaic virus (acmv). transformed plants were inoculated with a coat protein deletion mutant of acmv that induces mild systemic symptoms in control plants. several inoculated plants of transgenic lines cra1/3, cra1/4, cra2/1 and cra2/2 developed severe systemic symptoms typical of acmv. dna analysis revealed that, in these plants, recombinati ...	1998	9603342
nucleotide sequence and intergeminiviral homologies of the dna-a of papaya leaf curl geminivirus from india.	coat protein gene, rep protein gene and intergenic region of the genome of a whitefly transmitted geminivirus (wtg) causing severe leaf curl in papaya plants were pcr amplified, cloned and sequenced. comparison of the amino acid sequence of the putative coat protein product of papaya leaf curl virus (plcv) with some other mono and bipartite wtgs revealed a maximum of 89.8% homology with indian cassava mosaic virus. the genomic organization of plcv-india is similar to other wtgs with bipartite ge ...	1998	9635134
types of variation in dna-a among isolates of east african cassava mosaic virus from kenya, malawi and tanzania.	complete nucleotide sequences of the dna-a-like molecules of three east african cassava mosaic virus (eacmv) isolates from kenya (-k, 2801 nt) and malawi (-mh and -mk, both 2804 nt) were determined. these sequences were compared with that published for a tanzanian isolate (-t, 2801 nt) and the partial sequence of a third malawian isolate. intergenic region sequences of all isolates, and deduced amino acid sequences of their ac1 (rep) proteins, each formed a tightly related cluster that was disti ...	1998	9820161
molecular characterisation of a distinct south african cassava infecting geminivirus.	african cassava mosaic virus (acmv) and east african cassava mosaic virus (eacmv) are whitefly-transmitted geminiviruses (wtgs) which are widespread in cassava in africa and cause serious yield losses. recently, a new geminivirus affecting cassava in south africa (sacmv) has been reported. in this work sacmv was found to have dna-a and dna-b components. comparisons of amino acid sequences of the putative coat protein, and nucleotide sequences of the common region and a 687-bp dna b fragment of s ...	1998	9856107
infectivity of african cassava mosaic virus clones to cassava by biolistic inoculation.	clones of an african cassava mosaic virus isolate originating from nigeria (acmv-nog) were shown to be infectious to cassava by biolistic inoculation. the production of pseudorecombinants between acmv-nog and clones of an acmv isolate originating from kenya (acmv-k) indicated that the lack of infectivity of acmv-k to cassava was due to defect(s) in the dna b genomic component; this component encodes two proteins involved in cell-to-cell movement. this is the first demonstration of infectivity of ...	1998	9930204
transactivation of dianthin transgene expression by african cassava mosaic virus ac2.	we have recently described a novel strategy for engineering resistance to african cassava mosaic virus (acmv) in transgenic nicotiana benthamiana plants using a virus-inducible promoter to control the expression of a plant ribosome-inactivating protein (rip) transgene (y. hong et al., virology 220, 119-127, 1996). here, we have used a potato virus x (pvx) vector to express the acmv transactivator protein, ac2, in planta. we confirm that amplification of rip activity in transgenic plants is media ...	1997	9123846
a novel subviral agent associated with a geminivirus: the first report of a dna satellite.	numerous plant rna viruses have associated with them satellite (sat) rnas that have little or no nucleotide sequence similarity to either the viral or host genomes but are completely dependent on the helper virus for replication. we report here on the discovery of a 682-nt circular dna satellite associated with tomato leaf curl geminivirus (tlcv) infection in northern australia. this is the first demonstration that satellite molecules are not limited to rna viral systems. the dna satellite (tlcv ...	1997	9192696
efficient whitefly transmission of african cassava mosaic geminivirus requires sequences from both genomic components.	clones of two subgroup iii geminiviruses, the common strain of tomato golden mosaic virus (cstgmv) and african cassava mosaic virus originating from kenya (acmv-k), were shown to be non-transmissible by whitefiles. lack of transmissibility of cloned acmv-k was investigated by exchanging genomic components with a whitefly-transmissible acmv isolate from nigeria (acmv-nog). neither pseudorecombinant was transmissible, indicating that defects in both genomic components contributed to the lack of tr ...	1997	9225057
evidence that dna-a of a geminivirus associated with severe cassava mosaic disease in uganda has arisen by interspecific recombination.	geminivirus isolates associated with the epidemic of severe cassava mosaic disease in uganda were studied and compared with virus isolates from the part of uganda outside the epidemic area, and with african cassava mosaic virus (acmv) and east african cassava mosaic virus (eacmv). isolates of a novel type [the uganda variant (ugv)] were detected in severely affected plants from the epidemic area, whereas those from plants outside the epidemic area were typical of acmv. the complete nucleotide se ...	1997	9267014
resistance to geminivirus infection by virus-induced expression of dianthin in transgenic plants.	ribosome-inactivating proteins (rips) are naturally occurring plant toxins that exhibit antiviral activity against a diverse range of plant and animal viruses. here, the action of dianthin, a potent rip isolated from dianthus caryophyllus, has been exploited to engineer resistance to a plant dna virus, african cassava mosaic virus (acmv), in transgenic nicotiana benthamiana. to achieve this, dianthin has been expressed from the acmv virion-sense promoter that is transactivated by the product of ...	1996	8659104
complementation of african cassava mosaic virus ac2 gene function in a mixed bipartite geminivirus infection.	we have previously demonstrated that african cassava mosaic virus (acmv) dnas a and b efficiently complement the systemic spread of tomato golden mosaic virus (tgmv) dna a when co-agroinoculated onto nicotiana benthamiana. here, we show that a mixture of an acmv dna a ac2 mutant and dna b that is normally unable to systemically infect n. benthamiana can do so at low frequency when co-agroinoculated with tgmv dna a. analysis of viral dna showed that the ac2 mutation was retained during infection. ...	1995	7561766
regulation of african cassava mosaic virus complementary-sense gene expression by n-terminal sequences of the replication-associated protein ac1.	fragments of the african cassava mosaic virus (acmv) genome, cloned upstream of the beta-glucuronidase (gus) reporter gene in an expression cassette, were analysed for their ability to direct complementary-sense gene expression in tobacco protoplasts by measuring gus activity. five arbitrary domains (a-e) have been designated that contribute to the expression of ac1 (replication-associated protein) and ac4. consistent with earlier reports, ac1 gene expression was negatively regulated (80% reduct ...	1995	7595345
mutagenesis of the bc1 and bv1 genes of african cassava mosaic virus identifies conserved amino acids that are essential for spread.	the products of three open reading frames encoded by the bipartite geminiviruses have been implicated in viral spread: ac2, bv1 and bc1. alignment of the dna b encoded gene products, bv1 and bc1, from african cassava mosaic virus (acmv) with six other bipartite geminiviruses showed several highly conserved regions. specific amino acids were selected for mutagenic studies to ascertain the tolerance of the virus to change and to identify the regions within these two proteins required for normal fu ...	1995	7730816
molecular cloning of indian tomato leaf curl virus genome following a simple method of concentrating the supercoiled replicative form of viral dna.	dna-a and dna-b components of the genome of a whitefly transmitted virus causing yellowing and leaf curl in tomato (itlcv) were cloned following a simple procedure for isolation of the double stranded replicative form of viral dna from infected tomato plants. the method is based on extraction of total dna from infected plants followed by concentration of the double stranded replicative form of viral dna by an alkaline denaturation procedure identical to that used for isolation of plasmid dna fro ...	1995	7738150
chinese squash leaf curl virus: a new whitefly-transmitted geminivirus.	coat protein (cp) gene of the chinese squash leaf curl virus (sqlcv-c) was amplified through pcr, cloned and completely sequenced. based on the comparisons at the levels of both cp gene nucleotide and cp-deduced amino acid sequences with other geminiviruses, sqlcv-c is confirmed to be distinct from the american squash leaf curl virus (sqlcv-e). it is a new geminivirus transmitted by whitefly bemisia tabaci, which infects dicotyledonous plants and is more closely related to the indian cassava mos ...	1995	7755872
analysis of african cassava mosaic virus recombinants suggests strand nicking occurs within the conserved nonanucleotide motif during the initiation of rolling circle dna replication.	intact clones containing partial repeats of the genomic components of african cassava mosaic (acmv dnas a and b) are infectious when mechanically coinoculated onto nicotiana benthamiana. monomeric genomic components may be generated either by homologous recombination or, when two copies of the origin of replication (ori) are present, by a modified rolling circle replication mechanism in which nascent single-stranded dna is resolved by the introduction of nicks at both oris. dna b partial repeats ...	1995	7831830
tomato leaf curl geminivirus from india has a bipartite genome and coat protein is not essential for infectivity.	genomes of two isolates of tomato leaf curl geminivirus from india (tolcv-india) have been sequenced. tolcv-india contains a and b components, both of which are required for systemic movement and symptom development. the two isolates have 94% sequence identify but one isolate gave mild symptoms in nicotiana benthamiana and tomato. the genome organization of tolcv-india is similar to other whitefly-transmitted geminiviruses (wtgs) with bipartite genomes. however, it contains an additional orf, av ...	1995	7844539
lethal mutations within the conserved stem-loop of african cassava mosaic virus dna are rapidly corrected by genomic recombination.	the nonanucleotide motif taatattac occurs in the intergenic region of all geminiviruses that have been examined to date. the motif is invariably located within the loop of a potential stem-loop structure that has been implicated in viral dna replication. to investigate the contribution of these sequences to virus proliferation, african cassava mosaic virus (acmv) dna b mutants have been screened for their ability to infect nicotiana benthamiana when co-inoculated with dna a. mutants in which the ...	1994	7964630
expression of tgmv antisense rna in transgenic tobacco inhibits replication of bctv but not acmv geminiviruses.	transgenic tobacco plants expressing an antisense rna targeted against tomato golden mosaic virus (tgmv) show reduced/no symptoms and viral dna accumulation upon tgmv infection [5]. the targeted region includes the al1 gene, encoding an essential viral replication protein. this dna sequence is conserved in various other geminiviruses, suggesting they too might show inhibition of replication in these plants. we infected leaf material with african cassava mosaic virus (acmv) and beet curly top vir ...	1994	8111023
the nucleotide sequence and genome structure of mung bean yellow mosaic geminivirus.	complete nucleotide sequences of the infectious cloned dna components (dna 1 and dna 2) of mung bean yellow mosaic virus (mymv) were determined. mymv dna 1 and dna 2 consists of 2,723 and 2,675 nucleotides respectively. dna 1 and dna 2 have little sequence similarity except for a region of approximately 200 bases which is almost identical in the two molecules. analysis of open reading frames revealed nine potential coding regions for proteins of mol. wt. > 10,000, six in dna 1 and three in dna 2 ...	1993	8231962
nucleotide sequence evidence for the occurrence of three distinct whitefly-transmitted geminiviruses in cassava.	the complete nucleotide sequence of the dna of indian cassava mosaic virus (icmv) and a key part of that of a group b isolate of african cassava mosaic virus from malawi (acmv-m) were determined and compared at the nucleotide and encoded amino acid levels with the published sequences of an acmv group a isolate (acmv-k) and other whitefly-transmitted gemini-viruses (wtgs). the dna of icmv consists of two circular single-stranded molecules, dna-a [2815 nucleotides (nt)] and dna-b (2645 nt), which ...	1993	8245859
replication of the dna a component of african cassava mosaic virus in a heterologous system.	the capacity for autonomous replication of the dna a of african cassava mosaic virus (acmv), a member of the bipartite geminiviruses infecting dicotyledonous plants, has been compared in host and non-host cells. a derivative of the acmv dna a was transfected into tobacco and maize protoplasts. although acmv is not able to infect maize, replication of the dna a in maize protoplasts was observed to occur. the efficiency of replication was 10 to 20% of that seen in tobacco protoplasts. in both plan ...	1993	8277277
rapid production of full-length, infectious geminivirus clones by abutting primer pcr (abp-pcr).	the application of the polymerase chain reaction (pcr) method of dna amplification for the isolation of full-length, infectious clones of geminiviruses is described. non-overlapping, abutting 20-mer oligonucleotide primers were used to produce a linear product from the circular geminivirus genomic template. clones of african cassava mosaic virus (acmv) dna a, obtained by this method, were infectious following mechanical inoculation (in the presence of acmv dna b) onto nicotiana benthamiana. norm ...	1993	8360316
specificity of bipartite geminivirus movement proteins.	pseudorecombinants produced by exchanging genome components (dnas a and b) of the geminiviruses african cassava mosaic virus (acmv) and indian cassava mosaic virus (icmv), acmv, and tomato golden mosaic virus (tgmv), and tgmv and abutilon mosaic virus (abmv) are not infectious in their common host nicotiana benthamiana. in each case, dna a was unable to trans-replicate the heterogenomic dna b component in a n. benthamiana leaf disc assay. the non-viability of the pseudorecombinants has been expl ...	1993	8372440
complete nucleotide sequence of pepper huasteco virus: analysis and comparison with bipartite geminiviruses.	the complete nucleotide sequence of pepper huasteco geminivirus (phv) isolated in northern mexico was determined. the phv genome consists of two circular ssdna molecules of 2631 bases (phv a) and 2589 bases (phv b). phv has a genome organization typical of a bipartite geminivirus with four open reading frames (orfs) (ar1, al1, al2 and al3) in component a and two (br1 and bl1) in component b. an unexpected orf was found in the complementary sense strand of phv a. this orf, termed al5, is found en ...	1993	8409944
detection and possible functions of african cassava mosaic virus dna b gene products.	polyclonal antisera raised against synthetic oligopeptides have been used to detect the dna b gene products bv1 and bc1 of the geminivirus african cassava mosaic virus following sds-page fractionation of nicotiana benthamiana extracts. bv1 antiserum detected a soluble protein of 29 kda, consistent with the size predicted from sequence data. bc1 antiserum detected proteins of 37, 39, and 42 kda in addition to variable, less abundant species, all of which are larger than the predicted size of 34 k ...	1993	8517019
cytosine methylation inhibits replication of african cassava mosaic virus by two distinct mechanisms.	extrachromosomally replicating viral dna is usually free of cytosine methylation and viral templates methylated in vitro are poor substrates when used in replication assays. we have investigated the mechanism of inhibition of viral replication by dna methylation using as a model the dna a of african cassava mosaic virus. we have constructed two component helper systems which allow for separation of the transcriptional inhibition of viral genes necessary for replication from replication inhibitio ...	1993	7688453
serological relationships and epitope profiles of isolates of okra leaf curl geminivirus from africa and the middle east.	a panel of seven murine monoclonal antibodies (mabs) was raised against particles of okra leaf curl virus (olcv), a whitefly-transmitted geminivirus which is prevalent in west africa. the mabs detected at least six distinguishable epitopes, two continuous and four discontinuous. in tests with these mabs, relatively little antigenic variation was found among 24 olcv isolates from burkina faso, chad, ghana, ivory coast, nigeria, oman and saudi arabia, each virus isolate reacting with at least five ...	1993	7506936
rna-primed complementary-sense dna synthesis of the geminivirus african cassava mosaic virus.	the plant dna virus african cassava mosaic virus (acmv) is believed to replicate by a rolling circle mechanism. to investigate complementary-sense dna (lagging strand) synthesis, we have analysed the heterogenous form of complementary-sense dna (h3 dna) from infected nicotiana benthamiana by two-dimensional agarose gel electrophoresis and blot hybridisation. the presence of an rna moeity is demonstrated by comparison of results for nucleic acids resolved on neutral/alkaline and neutral/formamide ...	1992	1475192
the use of african cassava mosaic virus as a vector system for plants.	this paper describes the development of a gene-displacement vector based on dna1, one of two single stranded circular genomic components of a bipartite geminivirus, african cassava mosaic virus (acmv). the dna1 molecules of acmv were cloned as dimers into a plant transformation vector and the constructs have been integrated into tobacco protoplasts by peg-mediated dna transfer. in transgenic plants extrachromosomal copies of dna1 monomers could be detected. deletion of the coat protein-encoding ...	1992	1537557
inhibition of african cassava mosaic virus systemic infection by a movement protein from the related geminivirus tomato golden mosaic virus.	plant viruses encode proteins that mediate their movement through the host plant leading to the establishment of a systemic infection. we have analyzed the effect of tomato golden mosaic virus (tgmv) genes bl1 and br1, which are thought to be involved in the process of virus movement, on the infectivity of african cassava mosaic virus (acmv) in nicotiana benthamiana. recombinant genomes were constructed by replacing the acmv coat protein coding sequence with those of either bl1 or br1. replicati ...	1992	1546454
regulation of the activities of african cassava mosaic virus promoters by the ac1, ac2, and ac3 gene products.	dna fragments comprising each of the promoter regions from the geminivirus african cassava mosaic virus (acmv) were cloned into the puc18-based vector, pg1, producing transcriptional fusions with the beta-glucuronidase gene (gus) and nopaline synthase terminator sequence. the relative activity of each promoter construct was analyzed by a gus expression assay of extracts from nicotiana clevelandii protoplasts coelectroporated with the gus reporter constructs and constructs in which individual acm ...	1992	1585657
african cassava mosaic virus di dna interferes with the replication of both genomic components.	natural infections of the geminivirus african cassava mosaic virus (acmv) are known to be associated with low levels of defective interfering (di) dnas. recently it has been demonstrated that extrachromosomal copies of the di dna, mobilized and amplified from an integrated di dna dimer, can ameliorate acmv symptoms in transformed nicotiana benthamiana, providing a possible means for the control of cassava mosaic disease. to further understand the molecular basis of the interference phenomenon, w ...	1991	1853559
tomato yellow leaf curl virus: a whitefly-transmitted geminivirus with a single genomic component.	the genome of the tomato yellow leaf curl virus (tylcv), a bemisia tabaci-transmitted geminivirus, was cloned. all clones obtained were of one genomic molecule, analogous to dna a of african cassava mosaic virus. nucleotide sequence analysis of the tylcv genome showed that it comprises 2787 nucleotides, encoding six open reading frames, two on the virion strand and four on the complementary strand. all of them have counterparts in other geminiviruses. dimeric copies of the cloned viral genome we ...	1991	1926771
analysis of the potential promoter sequences of african cassava mosaic virus by transient expression of the beta-glucuronidase gene.	dna fragments from promoter regions of the geminivirus, african cassava mosaic virus, were cloned into pg1, a vector based on puc18, producing transcriptional fusions with the beta-glucuronidase (gus) gene and nopaline synthase termination sequence. the activity of each promoter construct was assessed by analysing the transient expression of gus in nicotiana clevelandii protoplasts. the results demonstrated that constructs containing the common region of dna a showed much stronger promoter activ ...	1991	1940874
mutational analysis of complementary-sense genes of african cassava mosaic virus dna a.	we have investigated the ability of african cassava mosaic virus dna a mutants, containing disrupted complementary-sense genes, to infect nicotiana benthamiana and to replicate in nicotiana tabacum protoplasts. three overlapping open reading frames (orfs) with the capacity to encode proteins with an mr greater than 10k (ac1, ac2 and ac3) are highly conserved between geminiviruses that infect dicotyledonous plants and one (ac4) is less well conserved. of these, only ac1 is a prerequisite for dna ...	1991	2033385
dna forms of the geminivirus african cassava mosaic virus consistent with a rolling circle mechanism of replication.	we have analysed dna from african cassava mosaic virus (acmv)-infected nicotiana benthamiana by two-dimensional agarose gel electrophoresis and detected acmv-specific dnas by blot-hybridisation. acmv dna forms including the previously characterised single-stranded, open-circular, linear and supercoiled dnas along with five previously uncharacterised heterogeneous dnas (h1-h5) were resolved. the heterogeneous dnas were characterised by their chromatographic properties on bnd-cellulose and their a ...	1991	2041773
mutagenesis of the ac3 open reading frame of african cassava mosaic virus dna a reduces dna b replication and ameliorates disease symptoms.	small insertions were made independently at each of four unique restriction sites on african cassava mosaic virus (acmv) dna a to disrupt the three overlapping complementary-sense open reading frames (orfs) herein designated ac1, ac2 and ac3. the dna a mutants were assayed for their infectivity by agroinoculation of monomeric constructs to nicotiana benthamiana plants containing chromosomal insertions of acmv dna b. disruption of the ac3 orf alone resulted in a delay and amelioration of disease ...	1991	2045787
nucleotide sequence of the infectious cloned dna components of african cassava mosaic virus (nigerian strain).		1990	2308831
geminivirus coat protein gene replacement alters insect specificity.	chimeric clones have been constructed in which the coat protein encoded by dna a of the bipartite genome of the geminivirus african cassava mosaic virus (acmv) has been replaced by that of beet curly top virus (bctv). constructs containing the coding region inserted in either orientation were infectious when co-inoculated with acmv dna b onto nicotiana benthamiana, producing symptoms typical of acmv infection. the onset of symptom production was delayed relative to plants inoculated with parenta ...	1990	2353465
defective viral dna ameliorates symptoms of geminivirus infection in transgenic plants.	nicotiana benthamiana was transformed with a single copy of a tandem repeat of subgenomic dna b isolated from plants infected with a kenyan isolate of the bipartite geminivirus african cassava mosaic virus. symptoms in transformed plants were less severe than in nontransformed controls when challenged with virus or cloned dna of kenyan or nigerian isolates. symptom amelioration was associated with the mobilization and amplification of the subgenomic dna, producing a comparable reduction in the a ...	1990	2385593
size reversion of african cassava mosaic virus coat protein gene deletion mutants during infection of nicotiana benthamiana.	mutants of african cassava mosaic virus containing extensive deletions across the coat protein gene that remove up to one-third of the genomic component have been constructed and shown to be infectious when mechanically inoculated onto nicotiana benthamiana by leaf abrasion. using n. tabacum protoplasts we demonstrate that mutant pclv.cp delta 11, containing a 712 bp deletion, is competent for replication in its deleted form. however, systemic spread of pclv. cp delta 11 and other deletion mutan ...	1989	2732690
indian cassava mosaic virus: ultrastructure of infected cells.	ultrastructural examination of leaf tissue of nicotiana benthamiana infected with indian cassava mosaic virus (icmv) revealed abnormalities in phloem and, occasionally, xylem cells. nuclei contained granular inclusion bodies which seemed to be largely composed of virus-like particles and were shown by immunogold labelling (igl) to be rich in icmv coat protein. later in infection, hollow spheres made up of fibrillar material were produced. virus coat protein was not a necessary component of these ...	1989	2794977
potential gene products of bean golden mosaic virus have higher sequence homologies to those of tomato golden mosaic virus than to those of cassava latent virus.	comparison of the nucleotide sequences of the dnas of bean golden mosaic virus (bgmv), tomato golden mosaic virus (tgmv) and cassava latent virus (clv) revealed a fairly close relationship between bgmv dna1, tgmv dna1, and clv dna1 and a comparatively distant relationship between bgmv dna2, tgmv dna2, and clv dna2. the 200-base region common to the two dnas of each virus had little sequence homology, except for a highly conserved 33-36 base sequence potentially capable of forming a stable hairpi ...	1988	3238924
delimitation of essential genes of cassava latent virus dna 2.	insertion and deletion mutagenesis of both extended open reading frames (orfs) of cassava latent virus dna 2 destroys infectivity. infectivity is restored by coinoculating constructs that contain single mutations within different orfs. although frequent intermolecular recombination produces dominant parental-type virus, mutants can be retained within the virus population indicating that they are competent for replication and suggesting that rescue can occur by complementation of trans acting gen ...	1988	3387209
cassava latent virus infections mediated by the ti plasmid of agrobacterium tumefaciens containing either monomeric or dimeric viral dna.	plant infections with cassava latent virus (clv) were mediated by the ti plasmid of agrobacterium tumefaciens containing either monomeric or dimeric copies of the virus genome. the clv dnas caused typical symptoms when they were inoculated in agrobacterium strains c58, lba4404 and a vire mutant a1026, but not other agrobacterium strains with mutations in other vir loci or an e. coli pola strain. virus-specific dna forms characteristic of normal clv infections were found after such infection. cha ...	1988	24272630
expression of a bacterial gene in plants mediated by infectious geminivirus dna.	a viable coat protein deletion mutant of cassava latent virus (clv) dna 1 has been isolated, suggesting that this geminivirus might be exploited as a gene replacement vector. an extensive deletion of 727 nucleotides within the coat protein gene renders dna 1 non-infectious. chimeric clones have been constructed in which the deleted coat protein open reading frame has been replaced by the coding region of the bacterial chloramphenicol acetyl transferase (cat) gene. infectivity is restored to dna ...	1988	16453850
structure and replication of geminivirus genomes.	the geminiviruses are a group of plant viruses containing single-stranded (ss) dna in particles comprising two quasi-icosahedral units. some are transmitted by whiteflies, others by leafhoppers. comparisons were made of the genome organization and expression of cassava latent virus (clv) and maize streak virus (msv) and beet curly top virus (bctv), each with distinct host range and insect vector species characteristics. from these studies, several indications as to the replication mechanism(s) a ...	1987	3503890
synthesis of viral dna forms in nicotiana plumbaginifolia protoplasts inoculated with cassava latent virus (clv); evidence for the independent replication of one component of the clv genome.	totipotent leaf mesophyll protoplasts of nicotiana plumbaginifolia, viviani were inoculated with cassava latent virus (clv) or with full length copies of clv genomic dnas 1 and 2 excised from replicative forms of m13 clones. virus specific dnas began to appear 48-72h after inoculation with virus or cloned dnas, coincident with the onset of host cell division. infected cells accumulated supercoiled forms of dnas 1 and 2 as well as progeny single-stranded (ss) virion (+) sense dnas representing ea ...	1986	3951986
infectious mutants of cassava latent virus generated in vivo from intact recombinant dna clones containing single copies of the genome.	intact recombinant dnas containing single copies of either component of the cassava latent virus genome can elicit infection when mechanically inoculated to host plants in the presence of the appropriate second component. characterisation of infectious mutant progeny viruses, by analysis of virus-specific supercoiled dna intermediates, indicates that most if not all of the cloning vector has been deleted, achieved at least in some cases by intermolecular recombination in vivo between dnas 1 and ...	1986	2875435
characterisation of dna forms associated with cassava latent virus infection.	in addition to the major encapsidated dna species found in preparations of cassava latent virus (genomic dnas 1 and 2) there are minor dna populations of twice (dimeric) and approximately half genome length. both minor species resemble the genomic dnas in that they are composed of predominantly circular single-stranded dna. all of these size groups have a corresponding covalently-closed circular double-stranded dna form in infected tissue. infectivity studies using cloned dnas 1 and 2 show that ...	1985	4000956
sequence homology among the coat proteins of gemini viruses.	the coat proteins of the gemini viruses - african cassava latent virus, tomato golden mosaic virus and maize streak virus - are shown to have reasonable to good amino acid sequence homology. it is suggested that the maize streak virus genome is ancestral and the bipartite genomes of the other viruses evolved from it.	1985	4026858
nucleotide sequence of bean golden mosaic virus and a model for gene regulation in geminiviruses.	we have sequenced the genome of bean golden mosaic virus, which comprises two circular single-stranded dna molecules (2646 and 2587 nucleotides long) of mostly unique sequence. comparison of the sequences of bean golden mosaic virus and of cassava latent virus, which share serological relationship but are very different in host range and geographical origin, shows that each virus has a unique 200-nucleotide sequence (common region) on each 2.6-kilobase molecule of its genome. the common regions ...	1985	16593562
major polyadenylated transcripts of cassava latent virus and location of the gene encoding coat protein.	the nucleotide sequences of infectious cloned dnas 1 and 2 of a kenyan isolate of cassava latent virus (clv) have been determined. five virus-specific polyadenylated transcripts have been identified and mapped either to the viral or complementary sense dnas of both components of the clv genome, confirming that transcription is bidirectional on both dnas. a major mrna has been translated in vitro to yield a 30 000 mol. wt. product, which is precipitated by antibodies raised against whole virus, a ...	1985	15918226
the nucleotide sequence of cloned wheat dwarf virus dna.	restriction analysis and cloning of virus-specific double-stranded dna isolated from plants infected with wheat dwarf virus (wdv) indicated that the virus genome, like that of maize streak virus (msv), consists of a single dna circle. the complete nucleotide sequence of cloned wdv dna (2749 nucleotides) has been determined. comparison of the potential coding regions in wdv dna with those in the dna of two strains of msv suggests that these viruses encode at least two functional proteins, the coa ...	1985	15938050
computer analysis identifies sequence homologies between potential gene products of maize streak virus and those of cassava latent virus and tomato golden mosaic virus.	the amino acid sequences of the putative polypeptides of maize streak virus (msv) have been systematically compared with those of cassava latent virus (clv) and tomato golden mosaic virus (tgmv) using the programme diagon (8).conserved sequences have been detected between peptides encoded by the complementary (-) sense of msv and those of clv and tgmv, viz; the 40 200 mr polypeptide of clv-1 (3) and the 40 285 mr polypeptide of tgmv-a (4) show extensive homologies with the 17 768 mr and 31 388 m ...	1985	24306572
complete nucleotide sequence of the infectious cloned dna components of tomato golden mosaic virus: potential coding regions and regulatory sequences.	the nucleotide sequences of the infectious cloned dna components of tomato golden mosaic virus (tgmv) have been determined. dna a (2588 nucleotides) and dna b (2508 nucleotides) have little sequence homology except for a region of 200 bases which is almost identical in the two molecules. analysis of open reading frames revealed six potential coding regions for proteins of mol. wt. >10 000, four in dna a and two in dna b. possible regulatory signals are identified and a model for bidirectional tr ...	1984	16453557
physical structure and genetic organisation of the genome of maize streak virus (kenyan isolate).	the structure of the maize streak virus genome (kenyan isolate, msv-k), as determined from the sequence of clones obtained from dna isolated from virus particles, is composed of one major dna component of about 2.6 kb. msv virion dna is partially double-stranded, composed of a full-length virion (v) strand and a short (70-80b) primer (p) strand. the primer strand has a fixed 5'-end capped with alkaline labile material, presumably 1-2 ribonucleotides. the msv genome has two major coding regions o ...	1984	6493977
the nucleotide sequence of maize streak virus dna.	the nucleotide sequence of the dna of maize streak virus (msv) has been determined. the data were accommodated into one dna circle of 2687 nucleotides, in contrast to previously characterised geminiviruses which have been shown to possess two circles of dna. comparison of the nucleotide sequences of the dna of msv with those of cassava latent virus (clv) and tomato golden mosaic virus (tgmv) showed no detectable homology. analysis of open reading frames revealed seven potential coding regions fo ...	1984	6526009