| dissecting the immune response to moloney murine sarcoma/leukemia virus-induced tumors by means of a dna vaccination approach. | the intramuscular inoculation of moloney murine sarcoma/leukemia (m-msv/m-mulv) retroviral complex gives rise to sarcomas that undergo spontaneous regression due to the induction of a strong immune reaction mediated primarily by cytotoxic t lymphocytes (ctl). we used a dna-based vaccination approach to dissect the ctl response against the gag and env proteins of m-msv/m-mulv in c57bl/6 (b6) mice and to evaluate whether plasmid dna-immunized mice would be protected against a subsequent challenge ... | 1999 | 9971811 |
| adaptation of the geminivirus bean yellow dwarf virus to dicotyledonous hosts involves both virion-sense and complementary-sense genes. | bean yellow dwarf virus (beydv) and maize streak virus (msv) belong to the geminivirus genus mastrevirus and have host ranges confined to dicotyledonous and monocotyledonous species, respectively. to investigate viral determinants of host range specificity, chimeras were constructed by exchanging their coding and non-coding regions. beydv chimeras containing msv orf v1, orf v2 or small intergenic region sequences, either individually or in various sequential combinations, replicated and produced ... | 1999 | 10073713 |
| generation of maize cell lines containing autonomously replicating maize streak virus-based gene vectors. | virion sense gene replacement derivatives of maize streak virus (msv) were constructed with selectable marker expression cassettes based on the bialaphos resistance gene (bar) and the camv 35s promoter. the effect on replication of increasing the genomic size was tested by including: (1) the 550-bp maize adhi intron and 68-bp tmv omega rna leader sequences upstream of the bar genes; and (2) a fusion between the bar and e. coli glutathione reductase (gor) genes. three recombinant viral vectors ra ... | 1999 | 10481741 |
| the induction of skeletal muscle hypertrophy by a ski transgene is promoter-dependent. | the chicken c-ski gene expresses at least three alternatively spliced messages. transgenic mice expressing proteins from cdna corresponding to two of these messages (fb27 and fb29) under the control of a murine sarcoma virus (msv) long terminal repeat (ltr) express the transgene in skeletal muscle and develop a muscular phenotype. both a biologically active form of c-ski and the msv ltr are required for the development of the muscular phenotype. the normal c-ski gene linked to two other tissue-s ... | 2000 | 10607904 |
| infection and transformation of dog cells with a modified sarcoma virus. | dog-embryo cell cultures were infected with a mixture of feline leukemia virus (fellv) and a modified murine (moloney) sarcoma virus msv(fellv). morphological alteration of the cells was observed 3 days post infection. virus progeny from the infected cultures increased 50- to 100-fold in foci of cellular alteration on dog cell cultures pretreated with diethylaminoethyl-dextran, but only twofold on cat embryo cultures similarly treated. the numbers of foci produced corresponded to a dual infectio ... | 1970 | 18605433 |
| eight decades of maize streak virus research. | maize streak virus (msv) (genus mastrevirus; family geminiviridae) causes what is considered the most important and widespread disease of maize in sub-saharan africa. maize streak was named by storey in 1925. since his classical work on the virus and its leafhopper vectors of the genus cicadulina china, msv has been the subject of intensive research. aspects concerning the geographical distribution, virus diversity, molecular characterization, vector-virus relationships and resistance breeding a ... | 2000 | 11137166 |
| murine sarcoma virus defectiveness. viral polymerase expression in murine and nonmurine host cells transformed by s + l - type murine sarcoma virus. | sarcoma virus-positive, leukemia virus-negative (s + l -) mouse cells transformed by defective but rescuable murine sarcoma virus (msv) release noninfectious type c virions with a quantitative deficiency of viral-type rna-dependent dna polymerase (rddp). human s + l - cells containing the same genome fail to express any detectable viral-type reverse transcriptase. to study this difference in msv expression, second-generation msv from the s + l - human cells is recloned in dog, mink, and back int ... | 1975 | 18621353 |
| cell-cycle, phase-specific activation of maize streak virus promoters. | it is believed that geminiviral dna replication is coupled to the cell-cycle regulatory complex of the plant cell and that the virus-early (complementary or c sense) gene products rep and repa may be able to manipulate the regulation of the cycle. in this study, we examined expression from the promoters of maize streak virus (msv) in transgenic maize plants and cells to determine whether they showed cell-cycle specificity. histochemical staining of plant roots containing "long and short" c-sense ... | 2001 | 11332725 |
| effect of porphyridium sp. polysaccharide on malignant cell transformation by moloney murine sarcoma virus. | the polysaccharide produced by the red microalga porphyridium sp. was highly inhibitory for cell transformation of mouse fibroblast cells by an msv-124 virus stock. this inhibition was most effective if the polysaccharide was added 2 h before or at the time of infection. the finding that the inhibition of cell transformation by musv-124 was reversible after removal of the polysaccharide suggested that porphyridium sp. polysaccharide inhibited a late step after provirus integration into the host ... | 2001 | 11497300 |
| spatial and temporal distribution of geminiviruses in leafhoppers of the genus cicadulina monitored by conventional and quantitative polymerase chain reaction. | abstract spatial and temporal distribution of maize streak virus (msv, family geminiviridae, genus mastrevirus) was monitored in the vector species cicadulina mbila and the nonvector species c. chinaï using conventional and real-time quantitative polymerase chain reaction. sustained feeding on msv-infected plants showed that virus accumulation reaches a maximum in c. chinaï, but not in c. mbila. after a 3-day acquisition access feeding period (aap), msv was detected in the gut, the hemolymph, an ... | 2002 | 18944141 |
| transmission of viral rna and dna to maize kernels by vascular puncture inoculation. | vascular puncture inoculation (vpi) is an effective technique for transmission of maize viruses without using arthropods or other biological vectors. it involves using a jeweler's engraving tool to push minuten pins through a droplet of virus inoculum toward the major vascular bundle in the scutellum of germinating kernels. here, vpi is shown to be useful for introducing rna and dna viral genomes into maize. maize dwarf mosaic potyvirus (mdmv) virions, mdmv genomic rna, foxtail mosaic potexvirus ... | 2001 | 11576640 |
| evaluation of maize streak virus pathogenicity in differentially resistant zea mays genotypes. | abstract we devised a rapid technique for the objective and precise assessment of both the pathogenicity of maize streak virus (msv) isolates and the msv resistance of maize genotypes. the technique involves the use of agroinoculation to infect maize seedlings and the objective symptom evaluation by quantification of infection rates, stunting, and chlorotic leaf areas. in assessing the msv resistance of 19 maize genotypes, we describe how the use of differentially virulent virus isolates enables ... | 1999 | 18944683 |
| microcomputer-based quantification of maize streak virus symptoms in zea mays. | abstract we investigated the use of computer-assisted image analysis techniques for the objective quantification of maize streak virus (msv) symptoms in zea mays. we compared independent duplicate evaluations of chlorotic lesion areas occurring on msv-infected leaves using visual assessment, a commercial image analysis system, and a custom image analysis system employing software developed in our laboratory. relative to visual assessments of disease severity, computer-assisted image analysis emp ... | 1998 | 18944921 |
| assessment of codivergence of mastreviruses with their plant hosts. | viruses that have spent most of their evolutionary time associated with a single host lineage should have sequences that reflect codivergence of virus and host. several examples for rna viruses of host-virus tree congruence are being challenged. dna viruses, such as mastreviruses, are more likely than rna viruses to have maintained a record of host lineage association. | 2008 | 19094195 |
| microfilaments and intermediate filaments in epithelial cells transformed by murine sarcoma or leukemia viruses. | the murine epithelial cell line mmc-e was used to study changes in the cytoskeletal organization associated with viral transformation of epithelial cells by two different viruses. the cells were transformed with moloney mouse sarcoma virus (msv) or murine leukemia virus (mulv). the expression of actin, myosin and of intermediate filament proteins in the cells was then studied. in mmc-e cells actin and myosin were organized as belt-like structures at the edges of the border cells of the cell isla ... | 1983 | 11596492 |
| design, synthesis, and biological evaluation of novel nucleoside and nucleotide analogues as agents against dna viruses and/or retroviruses. | a novel strategy was developed for the synthesis of n(7)-purine acyclic nucleosides 9 and 14. the key step involved the reaction between [2-(p-methoxyphenyloxy)ethoxy]methyl chloride and n(9)-tritylated nucleobases 6 or 11 followed by concomitant self-detritylation. n(7)-guanine acyclic nucleoside 9 exhibited antiviral activity, but was phosphorylated by both hsv and vero cell thymidine kinases. thus, it showed more potent cellular toxicity than acyclovir (2). n(7)-adenine acyclic nucleoside 14 ... | 2001 | 11606136 |
| experimental evidence indicating that mastreviruses probably did not co-diverge with their hosts. | despite the demonstration that geminiviruses, like many other single stranded dna viruses, are evolving at rates similar to those of rna viruses, a recent study has suggested that grass-infecting species in the genus mastrevirus may have co-diverged with their hosts over millions of years. this "co-divergence hypothesis" requires that long-term mastrevirus substitution rates be at least 100,000-fold lower than their basal mutation rates and 10,000-fold lower than their observable short-term subs ... | 2009 | 19607673 |
| identification of long intergenic region sequences involved in maize streak virus replication. | the main cis-acting control regions for replication of the single-stranded dna genome of maize streak virus (msv) are believed to reside within an approximately 310 nt long intergenic region (lir). however, neither the minimum lir sequence required nor the sequence determinants of replication specificity have been determined experimentally. there are iterated sequences, or iterons, both within the conserved inverted-repeat sequences with the potential to form a stem-loop structure at the origin ... | 2007 | 17485545 |
| maize streak virus-resistant transgenic maize: a first for africa. | in this article, we report transgene-derived resistance in maize to the severe pathogen maize streak virus (msv). the mutated msv replication-associated protein gene that was used to transform maize showed stable expression to the fourth generation. transgenic t2 and t3 plants displayed a significant delay in symptom development, a decrease in symptom severity and higher survival rates than non-transgenic plants after msv challenge, as did a transgenic hybrid made by crossing t2 hi-ii with the w ... | 2007 | 17924935 |
| immune complex disease in chronic viral infections. | chronic viral infections of animals associated with immune complex disease resemble a number of human disorders. at present, on the basis of showing (a) virus, host antiviral antibody, and c3 deposited in a granular pattern along the glomerular capillary wall and in the mesangia and (b) virus-host ig (presumably antiviral antibody) complexes in the circulation, immune complex disease occurs in chronic murine infections with lcm, ldv, msv, and adm. in addition, granular deposits in the glomeruli ... | 1971 | 19867377 |
| comparative analysis of panicum streak virus and maize streak virus diversity, recombination patterns and phylogeography. | panicum streak virus (pansv; family geminiviridae; genus mastrevirus) is a close relative of maize streak virus (msv), the most serious viral threat to maize production in africa. pansv and msv have the same leafhopper vector species, largely overlapping natural host ranges and similar geographical distributions across africa and its associated indian ocean islands. unlike msv, however, pansv has no known economic relevance. | 2009 | 19903330 |
| novel sugarcane streak and sugarcane streak réunion mastreviruses from southern africa and la réunion. | the sugarcane infecting streak viruses (sisvs) are mastreviruses (family geminiviridae) belonging to a group of "african streak viruses" (afsvs) that includes the economically devastating maize streak virus (msv). although there are three currently described sisv species (sugarcane streak virus [ssv], sugarcane streak egypt virus [ssev] and sugarcane streak réunion virus [ssrv]), only one strain variant has been fully sequenced for each of these species and as a result very little is known about ... | 2008 | 18175043 |
| a protocol for the rapid isolation of full geminivirus genomes from dried plant tissue. | a high-throughput method of isolating and cloning geminivirus genomes from dried plant material, by combining an extract-n-amp-based dna isolation technique with rolling circle amplification (rca) of viral dna, is presented. using this method an attempt was made to isolate and clone full geminivirus genomes/genome components from 102 plant samples, including dried leaves stored at room temperature for between 6 months and 10 years, with an average hands-on-time to rca-ready dna of 15 min per 20 ... | 2008 | 18280590 |
| transmission of maize streak virus by vascular puncture inoculation with unit-length genomic dna. | the infectivity of cloned unit-length genomes of maize streak virus (msv) was tested using vascular puncture inoculation (vpi). vpi of kernels with plasmid dna (puc19) carrying a tandem repeat of the msv genome produced 33+/-8% infection. similar plasmids carrying the unit-length msv genome were not infectious. if the msv genome was released from the plasmid prior to vpi, 16+/-4% of plants became infected. ligation of the free linear msv genome did not increase infectivity. the three infective i ... | 2003 | 12668274 |
| viral protein-nucleic acid interaction: south (north)-western blot. | maize streak virus (msv) genome has four open reading frames. c1 and c2 encoded by the complementary sense are required for virus replication, while v1 and v2 encoded by virion sense are required for infectivity. v1 encodes movement protein (mp), while v2 encodes coat protein (cp). deletion or mutation of msv cp does not prevent virus replication in single cells or protoplasts but leads to a loss of infectivity in the inoculated plant suggesting that msv cp is required for virus movement. toward ... | 2008 | 18370271 |
| a single amino acid change in the coat protein of maize streak virus abolishes systemic infection, but not interaction with viral dna or movement protein. | summary functional coat protein (cp) is important for host plant infection by monopartite geminiviruses. we identified a proline-cysteine-lysine (pck) motif at amino acids 180-182 of the maize streak virus (msv) cp that is conserved in most of the cereal-infecting mastreviruses. substitution of the lysine (k) with a valine (v) in the cp of msv to produce mutant msvcp182v abolished systemic infection in maize plants, although the mutant replicated around the inoculation site and, unlike other msv ... | 2001 | 20573010 |
| a new african streak virus species from nigeria. | the african streak viruses (afsvs) are a diverse group of mastrevirus species (family geminiviridae) that infect a wide variety of annual and perennial grass species across the african continent and its nearby indian ocean islands. six afsv species (of which maize streak virus is the best known) have been described. here we report the full genome sequences of eight isolates of a seventh afsv species: urochloa streak virus (usv), sampled from various locations in nigeria. despite there being good ... | 2008 | 18521534 |
| synthesis and antiviral activity of some 5'-n-phthaloyl-3'-azido-2',3'-dideoxythymidine analogues. | a variety of substituted 5'-n-phthaloyl-3'-azido-2',3'-dideoxythymidine derivatives has been evaluated for their activity against hiv-1, hiv-2 and moloney murine sarcoma virus (msv) in cell culture. most of the 3'-azido-2',3'-dideoxythymidine (azt, zidovudine) derivatives showed antiviral activity in the lower micromolar concentration range and there was a close correlation between their anti-hiv and anti-msv activity (r = 0.99). the adamantyl phthaloyl derivative was active at submicromolar con ... | 2003 | 14521330 |
| 6-[2-phosphonomethoxy)alkoxy]-2,4-diaminopyrimidines: a new class of acyclic pyrimidine nucleoside phosphonates with antiviral activity. | acyclic nucleoside phosphonate derivatives containing a pyrimidine base preferably bearing amino groups at c-2 and c-4 (dapym), and linked at the c-6 position to (s)-[3-hydroxy-2-(phosphonomethoxy)propoxy] (hpmpo), 2-(phosphonomethoxy) ethoxy (pmeo) or (r)-[2-(phosphonomethoxy)propoxy] (pmpo), display an antiviral sensitivity spectrum that closely mimic that of the parental (s)-hpmp-, pme- and (r)-pmp-purine derivatives. several pmeo-dapym derivatives proved as potent as pmea (adefovir) and (r)- ... | 2004 | 15571252 |
| a three-nucleotide mutation altering the maize streak virus rep prbr-interaction motif reduces symptom severity in maize and partially reverts at high frequency without restoring prbr-rep binding. | geminivirus infectivity is thought to depend on interactions between the virus replication-associated proteins rep or repa and host retinoblastoma-related proteins (prbr), which control cell-cycle progression. it was determined that the substitution of two amino acids in the maize streak virus (msv) repa prbr-interaction motif (llcne to llclk) abolished detectable repa-prbr interaction in yeast without abolishing infectivity in maize. although the mutant virus was infectious in maize, it induced ... | 2005 | 15722543 |
| the evolutionary value of recombination is constrained by genome modularity. | genetic recombination is a fundamental evolutionary mechanism promoting biological adaptation. using engineered recombinants of the small single-stranded dna plant virus, maize streak virus (msv), we experimentally demonstrate that fragments of genetic material only function optimally if they reside within genomes similar to those in which they evolved. the degree of similarity necessary for optimal functionality is correlated with the complexity of intragenomic interaction networks within which ... | 2005 | 16244707 |
| visualization of a primary anti-tumor immune response by positron emission tomography. | current methodologies that monitor immune responses rely on invasive techniques that sample tissues at a given point in time. new technologies are needed to elucidate the temporal patterns of immune responses and the spatial distribution of immune cells on a whole-body scale. we describe a noninvasive, quantitative, and tomographic approach to visualize a primary anti-tumor immune response by using positron emission tomography (pet). bone marrow chimeric mice were generated by engraftment of hem ... | 2005 | 16293690 |
| adaptive evolution by recombination is not associated with increased mutation rates in maize streak virus. | single-stranded (ss) dna viruses in the family geminiviridae are proving to be very useful in real-time evolution studies. the high mutation rate of geminiviruses and other ssdna viruses is somewhat mysterious in that their dna genomes are replicated in host nuclei by high fidelity host polymerases. although strand specific mutation biases observed in virus species from the geminivirus genus mastrevirus indicate that the high mutation rates in viruses in this genus may be due to mutational proce ... | 2012 | 23268599 |
| 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 |
| restoration of native folding of single-stranded dna sequences through reverse mutations: an indication of a new epigenetic mechanism. | we used in vivo (biological), in silico (computational structure prediction), and in vitro (model sequence folding) analyses of single-stranded dna sequences to show that nucleic acid folding conservation is the selective principle behind a high-frequency single-nucleotide reversion observed in a three-nucleotide mutated motif of the maize streak virus replication associated protein (rep) gene. in silico and in vitro studies showed that the three-nucleotide mutation adversely affected rep nuclei ... | 2006 | 16427599 |
| fluvastatin does not elevate periosteal osteogenesis induce by moloney sarcoma virus (msv) in mice. | several studies have demonstrated the pleiotropic effects of statins. since wang and associates reported that in rabbits lovastatin reduced steroid-induced bone loss, numerous authors have confirmed these data, however, others have reported conflicting results. in this study, the effects of fluvastatin on bone formation were investigated in early and late phase of osteogenesis. in the first set of experiments (early phase of osteogenesis) cfw/ll mice were randomly divided into three groups. two ... | 2006 | 16531631 |
| pronounced in vitro and in vivo antiretroviral activity of 5-substituted 2,4-diamino-6-[2-(phosphonomethoxy)ethoxy] pyrimidines. | to discover new potent and selective anti-human immunodeficiency virus (hiv) acyclic nucleoside phosphonate (anp) drugs with in vivo antiretroviral activity. | 2007 | 17124193 |
| successful application of fta classic card technology and use of bacteriophage phi29 dna polymerase for large-scale field sampling and cloning of complete maize streak virus genomes. | leaf samples from 155 maize streak virus (msv)-infected maize plants were collected from 155 farmers' fields in 23 districts in uganda in may/june 2005 by leaf-pressing infected samples onto fta classic cards. viral dna was successfully extracted from cards stored at room temperature for 9 months. the diversity of 127 msv isolates was analysed by pcr-generated rflps. six representative isolates having different rflp patterns and causing either severe, moderate or mild disease symptoms, were chos ... | 2007 | 17174409 |
| inhibition of human immunodeficiency virus type 1 transcription by n-aminoimidazole derivatives. | this study describes the mechanism of antiviral action of the n-aminoimidazole derivatives which exclusively inhibit retroviruses such as hiv-1, hiv-2, siv and msv. these antiretroviral compounds, with lead prototype nr-818, were found to inhibit hiv-1 replication at the transcriptional level. analysis of each individual step of viral transcription, including transcriptional activation mediated by nf-kappab, the chromatin remodeling process at the viral promoter and viral mrna transcription medi ... | 2007 | 17459445 |
| a novel sugarcane-infecting mastrevirus from south africa. | the sugarcane-infecting streak viruses (sisvs) are a diverse collection of mastreviruses (family geminiviridae) within the african streak virus group. four sisvs have currently been described, including the well-characterized maize streak virus. here, we present a full annotated sequence record of an isolate of a new sisv species, saccharum streak virus (sacsv), isolated in south africa. the isolate shares less than 66% identity with any other mastrevirus, but is most closely related to urochloa ... | 2009 | 19756359 |
| maize streak virus: an old and complex 'emerging' pathogen. | maize streak virus (msv; genus mastrevirus, family geminiviridae) occurs throughout africa, where it causes what is probably the most serious viral crop disease on the continent. it is obligately transmitted by as many as six leafhopper species in the genus cicadulina, but mainly by c. mbila naudé and c. storeyi. in addition to maize, it can infect over 80 other species in the family poaceae. whereas 11 strains of msv are currently known, only the msv-a strain is known to cause economically sign ... | 2010 | 20078771 |
| peripheral blood and lymphatic organs in balb/c mice during the progressive and regressive phases of moloney sarcoma development. | blood cell counts, differential blood cell counts and weights of the spleen and peripheral lymph nodes draining the area of lesions induced by moloney sarcoma virus inoculation into the quadriceps shank muscles of inbred balb/c mice were examined at various stages of tumor development and regression. the blood cell count remained constant through the observation period up to 27 days post tumor development and regression. differential counts revealed some changes in the cellular composition of th ... | 2010 | 20420189 |
| activation of geminivirus v-sense promoters in roots is restricted to nematode feeding sites. | obligate sedentary endoparasitic nematodes, such as the root-knot and cyst nematodes, elicit the differentiation of specialized nematode nurse or feeding cells [nematode feeding sites (nfs), giant cells and syncytia, respectively]. during nfs differentiation, marked changes in cell cycle progression occur, partly similar to those induced by some geminiviruses. in this work, we describe the activation of v-sense promoters from the maize streak virus (msv) and wheat dwarf virus (wdv) in nfs formed ... | 2010 | 20447288 |
| effects of time of initial exposure to msv sarcoma on bone induction by dentine matrix implants and on orthotopic femora. | hcl-demineralized murine lower incisors were implanted intramuscularly into syngeneic balb/c mice to induce heterotopic osteogenesis. implants were exposed at the early, preosteogenic stage (4), or at the later, osteogenic stage (12) to the moloney sarcoma virus (msv), which within 3-4 days results in a sarcoma. the yield of bone induction was determined by weight of dry bone mass following naoh hydrolysis of soft tissues. to verify the effect of this sarcoma on orthotopic local femoral bone, th ... | 2010 | 20957093 |
| viable chimaeric viruses confirm the biological importance of sequence specific maize streak virus movement protein and coat protein interactions. | a variety of interactions between up to three different movement proteins (mps), the coat protein (cp) and genomic dna mediate the inter- and intra-cellular movement of geminiviruses in the genus begomovirus. although movement of viruses in the genus mastrevirus is less well characterized, direct interactions between a single mp and the cp of these viruses is also clearly involved in both intra- and intercellular trafficking of virus genomic dna. however, it is currently unknown how specific the ... | 2008 | 18489800 |
| behavioral responses of the leafhopper, cicadulina storeyi china, a major vector of maize streak virus, to volatile cues from intact and leafhopper-damaged maize. | the chemical ecology of the leafhopper, cicadulina storeyi china (homoptera: cicadellidae), an important vector of maize streak virus (msv), was studied with a view to developing novel leafhopper control strategies in sub-saharan africa. choice tests using a y-tube olfactometer revealed that odors from uninfested maize seedlings (zea mays cv. delprim) were significantly more attractive to c. storeyi than odors from c. storeyi-infested seedlings. headspace samples of volatile organic compounds (v ... | 2010 | 21191806 |
| revertants of mouse cells transformed by murine sarcoma virus. iii. metastable expression of virus functions in revertants retransformed by murine sarcoma virus. | 3t3fl cells transformed by the moloney murine sarcoma virus (msv) (sarcoma positive, leukemia negative, s+l- cells) segregate spontaneous flat revertants. these s-l- revertants do not release msv upon superinfection with mulv but are susceptible to a second cycle of single-hit msv transformation. the behavior and nature of second-cycle msv transformed revertants were followed by successive clonal generations. the second transformation by msv resulted in a number of metastable states. the simples ... | 1974 | 18620232 |
| recombination, decreased host specificity and increased mobility may have driven the emergence of maize streak virus as an agricultural pathogen. | maize streak virus (msv; family geminiviridae, genus mastrevirus), the causal agent of maize streak disease, ranks amongst the most serious biological threats to food security in subsaharan africa. although five distinct msv strains have been currently described, only one of these - msv-a - causes severe disease in maize. due primarily to their not being an obvious threat to agriculture, very little is known about the 'grass-adapted' msv strains, msv-b, -c, -d and -e. since comparing the genetic ... | 2008 | 18753214 |
| synthesis and antiviral activity of n9-[3-fluoro-2-(phosphonomethoxy)propyl] analogues derived from n6-substituted adenines and 2,6-diaminopurines. | an efficient method for the synthesis of n(9)-[3-fluoro-2-(phosphonomethoxy)propyl] (fpmp) derivatives of purine bases has been developed. both (r)- and (s)-enantiomers of the n(6)-substituted fpmp derivatives of adenine and 2,6-diaminopurine were prepared and their anti-human immunodeficiency virus (hiv) and anti-moloney murine sarcoma virus (msv) activity was evaluated. whereas none of the 6-substituted fpmpa derivatives showed any antiviral activity, several fpmpdap derivatives had a moderate ... | 2011 | 21429755 |
| experimental observations of rapid maize streak virus evolution reveal a strand-specific nucleotide substitution bias. | recent reports have indicated that single-stranded dna (ssdna) viruses in the taxonomic families geminiviridae, parvoviridae and anellovirus may be evolving at rates of approximately 10(-4) substitutions per site per year (subs/site/year). these evolution rates are similar to those of rna viruses and are surprisingly high given that ssdna virus replication involves host dna polymerases with fidelities approximately 10,000 times greater than those of error-prone viral rna polymerases. although hi ... | 2008 | 18816368 |
| biological and genomic sequence characterization of maize streak virus isolates from wheat. | abstract maize streak virus (msv) is best known as the causal agent of maize streak disease. however, only a genetically uniform subset of the viruses within this diverse species is actually capable of producing severe symptoms in maize. whereas these "maize-type" viruses all share greater than 95% sequence identity, msv strains isolated from grasses may share as little as 79% sequence identity with the maize-type viruses. here, we present the complete genome sequences and biological characteriz ... | 2002 | 18944143 |
| dating the origins of the maize-adapted strain of maize streak virus, msv-a. | maize streak virus (msv), which causes maize streak disease (msd), is one of the most serious biotic threats to african food security. here, we use whole msv genomes sampled over 30 years to estimate the dates of key evolutionary events in the 500 year association of msv and maize. the substitution rates implied by our analyses agree closely with those estimated previously in controlled msv evolution experiments, and we use them to infer the date when the maize-adapted strain, msv-a, was generat ... | 2009 | 19692547 |
| a high degree of african streak virus diversity within nigerian maize fields includes a new mastrevirus from axonopus compressus. | the a-strain of maize streak virus (msv-a; genus mastrevirus, family geminiviridae), the causal agent of maize streak disease, places a major constraint on maize production throughout sub-saharan africa. in west-african countries such as nigeria, where maize is not cultivated year-round, this msv strain is forced to overwinter in non-maize hosts. in order to both identify uncultivated grasses that might harbour msv-a during the winter season and further characterise the diversity of related maiz ... | 2014 | 24796552 |
| replicative intermediates of maize streak virus found during leaf development. | geminiviruses of the genera begomovirus and curtovirus utilize three replication modes: complementary-strand replication (csr), rolling-circle replication (rcr) and recombination-dependent replication (rdr). using two-dimensional gel electrophoresis, we now show for the first time that maize streak virus (msv), the type member of the most divergent geminivirus genus, mastrevirus, does the same. although mastreviruses have fewer regulatory genes than other geminiviruses and uniquely express their ... | 2010 | 20032206 |
| extensive recombination-induced disruption of genetic interactions is highly deleterious but can be partially reversed by small numbers of secondary recombination events. | although homologous recombination can potentially provide viruses with vastly more evolutionary options than are available through mutation alone, there are considerable limits on the adaptive potential of this important evolutionary process. primary among these is the disruption of favorable coevolved genetic interactions that can occur following the transfer of foreign genetic material into a genome. although the fitness costs of such disruptions can be severe, in some cases they can be rapidl ... | 2014 | 24789787 |
| a rep-based hairpin inhibits replication of diverse maize streak virus isolates in a transient assay. | maize streak disease, caused by the a-strain of the african endemic geminivirus, maize streak mastrevirus (msv-a), threatens the food security and livelihoods of subsistence farmers throughout sub-saharan africa. using a well-established transient expression assay, we investigated the potential of a spliceable-intron hairpin rna (hprna) approach to interfere with msv replication. two strategies were explored: (1) an inverted repeat of a 662-bp portion of the msv replication-associated protein ge ... | 2011 | 21653753 |
| large accumulations of maize streak virus in the filter chamber and midgut cells of the leafhopper vector cicadulina mbila. | maize streak virus (msv, mastrevirus, geminiviridae) is persistently transmitted by cicadulina mbila, apparently without propagation in its leafhopper vector. msv was shown earlier by quantitative pcr to accumulate in the alimentary canal of c. mbila. we examined the alimentary canals of c. mbila leafhoppers that acquired msv from diseased plants for various acquisition access periods (aap) by immunofluorescence confocal laser scanning microscopy (iclsm) and by immunogold labelling transmission ... | 2009 | 19151912 |
| rapid host adaptation by extensive recombination. | experimental investigations into virus recombination can provide valuable insights into the biochemical mechanisms and the evolutionary value of this fundamental biological process. here, we describe an experimental scheme for studying recombination that should be applicable to any recombinogenic viruses amenable to the production of synthetic infectious genomes. our approach is based on differences in fitness that generally exist between synthetic chimaeric genomes and the wild-type viruses fro ... | 2009 | 19218220 |
| reconstructing the history of maize streak virus strain a dispersal to reveal diversification hot spots and its origin in southern africa. | maize streak virus strain a (msv-a), the causal agent of maize streak disease, is today one of the most serious biotic threats to african food security. determining where msv-a originated and how it spread transcontinentally could yield valuable insights into its historical emergence as a crop pathogen. similarly, determining where the major extant msv-a lineages arose could identify geographical hot spots of msv evolution. here, we use model-based phylogeographic analyses of 353 fully sequenced ... | 2011 | 21715477 |
| Recombination hotspots and host susceptibility modulate the adaptive value of recombination during maize streak virus evolution. | ABSTRACT: BACKGROUND: Maize streak virus -strain A (MSV-A; Genus Mastrevirus, Family Geminiviridae), the maize-adapted strain of MSV that causes maize streak disease throughout sub-Saharan Africa, probably arose between 100 and 200 years ago via homologous recombination between two MSV strains adapted to wild grasses. MSV recombination experiments and analyses of natural MSV recombination patterns have revealed that this recombination event entailed the exchange of the movement protein - coat p ... | 2011 | 22136133 |
| detection of a non-structural protein of m r 11 000 encoded by the virion dna of maize streak virus. | a polypeptide of approximately 11 000 daltons (11 kda protein) encoded by an open reading frame (10.9 orf) from the virion sense of maize streak virus (msv) dna has been detected among the products of in vitro translation reactions programmed with rna from infected maize plants and also in total protein extracts from infected leaves. the 11 kda protein has not been detected in virions and is therefore proposed to have a nonstructural role.viral dna with an additional in-frame translation stop co ... | 1988 | 24272158 |
| identification and molecular characterization of a novel sugarcane streak mastrevirus and an isolate of the a-strain of maize streak virus from sugarcane in nigeria. | sugarcane and maize plants showing symptoms typical of those described for the so-called "african streak viruses" (afsvs) were encountered during field surveys conducted from february to july 2015 to document viruses infecting both crops across the northern guinea savannah region of nigeria. as part of this study, two categories of complete mastrevirus-like genome sequences were obtained from nine samples (maize = 2; sugarcane = 7). in pairwise comparisons, the full-length genomes of the first s ... | 2017 | 27815694 |
| the role of kenya in the trans-african spread of maize streak virus strain a. | maize streak virus (msv), the causal agent of maize streak disease (msd), is the most important viral pathogen of africa's staple food crop, maize. previous phylogeographic analyses have revealed that the most widely-distributed and common msv variant, msv-a1, has been repeatedly traversing africa over the past fifty years with long-range movements departing from either the lake victoria region of east africa, or the region around the convergence of zimbabwe, south africa and mozambique in south ... | 2017 | 28192163 |
| fine mapping of msv1, a major qtl for resistance to maize streak virus leads to development of production markers for breeding pipelines. | msv1 , the major qtl for msv resistance was delimited to an interval of 0.87 cm on chromosome 1 at 87 mb and production markers with high prediction accuracy were developed. maize streak virus (msv) disease is a devastating disease in the sub-saharan africa (ssa), which causes significant yield loss in maize. resistance to msv has previously been mapped to a major qtl (msv1) on chromosome 1 that is germplasm and environment independent and to several minor loci elsewhere in the genome. in this s ... | 2015 | 26081946 |
| mapping the distribution of maize streak virus genotypes across the forest and transition zones of ghana. | throughout sub-saharan africa, maize streak virus strain a (msv-a), the causal agent of maize streak disease (msd), is an important biological constraint on maize production. in november/december 2010, an msd survey was carried out in the forest and transition zones of ghana in order to obtain msv-a virulence sources for the development of msd-resistant maize genotypes with agronomic properties suitable for these regions. in 79 well-distributed maize fields, the mean msd incidence was 18.544 % a ... | 2015 | 25344899 |
| inducible resistance to maize streak virus. | maize streak virus (msv), which causes maize streak disease (msd), is the major viral pathogenic constraint on maize production in africa. type member of the mastrevirus genus in the family geminiviridae, msv has a 2.7 kb, single-stranded circular dna genome encoding a coat protein, movement protein, and the two replication-associated proteins rep and repa. while we have previously developed msv-resistant transgenic maize lines constitutively expressing "dominant negative mutant" versions of the ... | 2014 | 25166274 |
| priming of production in maize of volatile organic defence compounds by the natural plant activator cis-jasmone. | cis-jasmone (cj) is a natural plant product that activates defence against herbivores in model and crop plants. in this study, we investigated whether cj could prime defence in maize, zea mays, against the leafhopper, cicadulina storeyi, responsible for the transmission of maize streak virus (msv). priming occurs when a pre-treatment, in this case cj, increases the potency and speed of a defence response upon subsequent attack on the plant. here, we tested insect responses to plant volatile orga ... | 2013 | 23840295 |
| replication modes of maize streak virus mutants lacking repa or the repa-prbr interaction motif. | the plant-infecting mastreviruses (family geminiviridae) express two distinct replication-initiator proteins, rep and repa. although repa is essential for systemic infectivity, little is known about its precise function. we therefore investigated its role in replication using 2d-gel electrophoresis to discriminate the replicative forms of maize streak virus (msv) mutants that either fail to express repa (repa(-)), or express repa that is unable to bind the plant retinoblastoma related protein, p ... | 2013 | 23679984 |
| a novel maize-infecting mastrevirus from la réunion island. | despite extensive sampling, only one virus belonging to the genus mastrevirus of the family geminiviridae, maize streak virus (msv), has until now been detected in maize with maize streak disease (msd) symptoms. here, we report for the first time a second, highly divergent, mastrevirus isolated from two maize plants displaying characteristic msd-like symptoms, sampled on the south-west indian ocean island, la réunion. the two isolates shared <57 % genome-wide identity with all other known mastre ... | 2012 | 22543634 |
| molecular characterisation of dicot-infecting mastreviruses from australia. | monocotyledonous and dicotyledonous plant infecting mastreviruses threaten various agricultural systems throughout africa, eurasia and australasia. in australia three distinct mastrevirus species are known to infect dicotyledonous hosts such as chickpea, bean and tobacco. amongst 34 new "dicot-infecting" mastrevirus full genome sequences obtained from these hosts we discovered one new species, four new strains, and various variants of previously described mastrevirus species. besides providing a ... | 2012 | 22406325 |
| genetic mapping of maize streak virus resistance from the mascarene source. ii. resistance in line cirad390 and stability across germplasm. | the streak disease has a major effect on maize in sub-saharan africa. various genetic factors for resistance to the virus have been identified and mapped in several populations; these factors derive from different sources of resistance. we have focused on the réunion island source and have recently identified several factors in the d211 line. a second very resistant line, cirad390, was crossed to the same susceptible parent, b73. the linkage map comprised 124 rflp markers, of which 79 were commo ... | 1999 | 22665188 |
| genetic mapping of maize streak virus resistance from the mascarene source. i. resistance in line d211 and stability against different virus clones. | maize streak virus (msv) disease may cause significant grain yield reductions in maize in africa. réunion island maize germplasm is a proven source of strong resistance. its genetic control was investigated using 123 rflp markers in an f(2) population of d211 (resistant) × b73 (susceptible). this population of 165 f(2:3) families was carefully evaluated in harare (zimbabwe) and in réunion. artificial infestation was done with viruliferous leafhoppers. each plant was rated weekly six times after ... | 1999 | 22665187 |
| specificity of agrobacterium-mediated delivery of maize streak virus dna to members of the gramineae. | parameters affecting the efficiency of agroinfection of maize streak virus (msv) in maize have been determined. monomeric units, cloned at a number of sites in the msv genome were not infectious but multimeric units containing partial duplications were equally as infectious as complete tandem dimeric clones. inoculation of tandem dimeric units conjugated into different strains of agrobacterium showed that both a. tumefaciens and a. rhizogenes were able to transfer dna to maize and this ability w ... | 1989 | 24272715 |
| molecular diversity, geographic distribution and host range of monocot-infecting mastreviruses in africa and surrounding islands. | maize streak virus (msv), an important pathogen of maize in africa, is the most extensively studied member of the mastrevirus genus in the family geminiviridae. comparatively little is known about other monocot-infecting african mastreviruses, most of which infect uncultivated grasses. here we determine the complete sequences of 134 full african mastrevirus genomes from predominantly uncultivated poaceae species. based on established taxonomic guidelines for the genus mastrevirus, these genomes ... | 2017 | 28687345 |
| quasicrystalline and crystalline types of local protein order in capsids of small viruses. | like metal alloys and micellar systems in soft matter, the viral capsid structures can be of crystalline and quasicrystalline types. we reveal the local quasicrystalline order of proteins in small spherical viral capsids using their nets of dodecahedral type. we show that the structure of some of the viral shells is well described in terms of a chiral pentagonal tiling, whose nodes coincide with centers of mass of protein molecules. the chiral protein packing found in these capsids originates fr ... | 2017 | 28488589 |