Publications

characterization of a virus-specific proteolytic activity processing the gag precursor of the simian sarcoma-associated virus.	the proteolytic processing of the gag precursor polypeptide pr65gag of simian sarcoma-associated virus (ssav) has been studied in vivo and in vitro. in ssav-infected cells (i.e., in vivo) proteins of 52 and 38 kda and the viral protein p30 could be immunoprecipitated with anti-p30 serum. this cleavage pattern is only in part imitated by in vitro cleavage of the isolated pr65gag with avian myeloblastosis virus (amv) protease p15. however, in vitro incubation of isolated pr65gag with detergent-dis ...	1987	3027976
expression of alfalfa mosaic virus coat protein gene confers cross-protection in transgenic tobacco and tomato plants.	a chimeric gene encoding the alfalfa mosaic virus (almv) coat protein was constructed and introduced into tobacco and tomato plants using ti plasmid-derived plant transformation vectors. the progeny of the self-fertilized transgenic plants were significantly delayed in symptom development and in some cases completely escaped infection after inoculated with almv. the inoculated leaves of the transgenic plants had significantly reduced numbers of lesions and accumulated substantially lower amounts ...	1987	16453764
expression of alfalfa mosaic virus rna 4 in transgenic plants confers virus resistance.	agrobacterium-mediated transfer from a binary vector was used to produce transgenic nicotiana tabacum plants that expressed coat protein of the plant virus, alfalfa mosaic virus (amv). expression levels of the chimeric gene, which was under the control of the cauliflower mosaic virus 19s promoter, were determined in primary transformed plants, in the progeny from self-fertilization and in the progeny from crosses to normal tobacco. rna transcripts that were of the expected size as well as a prot ...	1987	16453779
expression of alfalfa mosaic virus and tobacco rattle virus coat protein genes in transgenic tobacco plants.	using the agrobacterium tumefaciens binary vector system, a chimeric gene consisting of the cauliflower mosaic virus 35 s promoter, alfalfa mosaic virus (aimv) coat protein (cp) cistron, and the nopaline synthase polyadenylation signal was integrated into the genome of nicotiana tabacum cv. samsun nn. in 70% of the transgenic tobacco plants the chimeric mrna and its translation product could be detected. cp accumulated to levels up to 0.05% of the soluble leaf protein. the accumulation was indep ...	1987	18644569
non-structural proteins and rnas of alfalfa mosaic virus synthesized in tobacco and cowpea protoplasts.	three proteins, reacting specifically with sera raised against synthetic peptides identical to c-terminal amino acid sequences in alfalfa mosaic virus (aimv) proteins p1, p2, and p3 translated in vitro from the aimv rnas 1, 2, and 3, respectively, were for the first time observed in tobacco and cowpea protoplasts. part of p2 is post-translationally modified in protoplasts, because the anti-p2 serum reacted also with a protein migrating slower than p2 itself. the modification reported for p3 in i ...	1987	18644580
analysis of the mechanism of protection in transgenic plants expressing the potato virus x coat protein or its antisense rna.	transgenic tobacco plants engineered to express either the potato virus x (pvx) coat protein (cp+) or the antisense coat protein transcript (cp-antisense) were protected from infection by pvx, as indicated by reduced lesion numbers on inoculated leaves, delay or absence of systemic symptom development and reduction in virus accumulation in both inoculated and systemic leaves. the extent of protection observed in cp+ plants primarily depended upon the level of expression of the coat protein. plan ...	1988	16453840
dihydrothymidine and thymidine glycol triphosphates as substrates for dna polymerases: differential recognition of thymine c5-c6 bond saturation and sequence specificity of incorporation.	the ability of dihydrothymidine (dhdttp) and thymidine glycol (dttp-gly) 5'-triphosphates to serve as substrates for different dna polymerases was investigated. dhdttp but not dttp-gly was used as a substrate by e. coli dna polymerase i (pol i). within the detection limit of the assay used, neither t4 dna polymerase nor avian myeloblastosis virus (amv) reverse transcriptase used dhdttp or dttp-gly as substrates. the ability of dhdttp and dttp-gly to undergo enzyme-catalyzed turnover to the monop ...	1988	3060857
studies on the mechanism of translational enhancement by the 5'-leader sequence of tobacco mosaic virus rna.	translation of foreign mrnas is enhanced by a cis-acting derivative (omega') of the 5'-leader sequence (omega) of tobacco mosaic virus rna (vulgare strain). to explain this effect we have conducted several experiments in vitro. 1. the presence of various 5'-terminal sequences, including omega', did not significantly increase the half-lives of chloramphenicol acetyltransferase (cat) or neomycin phosphotransferase (nptii) mrnas in wheat-germ extract. also, a long leader sequence, unrelated to omeg ...	1988	2841127
a point mutation in the dna binding domain of the v-myb oncogene of e26 virus confers temperature sensitivity for transformation of myelomonocytic cells.	we have molecularly cloned a mutant of the v-myb, ets-containing e26 avian leukemia virus which is temperature sensitive for the transformation of myeloid cells. cells infected with this mutant, ts21e26, are immature at 37 degrees c and can be induced to differentiate into resting, macrophage-like cells when shifted to 42 degrees c. the sequence of ts21e26 reveals a single relevant nucleotide alteration resulting in a threonine to arginine change in the highly conserved, putative dna binding v-m ...	1988	2852341
a centrifugation method for separation of plant viral genomic and subgenomic rnas.	using alfalfa mosaic virus (amv) as a model, a simple method for separating plant viral genomic rnas from their subgenomic counterparts was established. the method relies on sucrose gradient fractionation under carefully selected conditions of centrifugation and fraction collection. the rna components are recovered in nearly quantitative yield and have full biological activity as measured by infectivity of the reconstituted rnas in suitable protoplasts and plant hosts. the individual rnas, on th ...	1988	3181424
proto-oncogene expression in chicken leukemic cells induced by avian myeloblastosis virus.	sixteen proto-oncogenes which have generated retroviral oncogenes were tested for their expression in chicken leukemic cells induced by avian myeloblastosis virus (amv) and five were found to be expressed (c-ets, c-fps, c-mht, c-myc, and c-rel). the size of the c-fps transcript (4.0 kb) was not in good agreement with the size (approximately 3.0 kb) previously reported but was uniform in the leukemic cells from 10 different chickens. the size of the other proto-oncogene transcripts appeared norma ...	1988	3226723
in vitro transcription and translational efficiency of chimeric sp6 messenger rnas devoid of 5' vector nucleotides.	a plasmid containing the bacteriophage sp6 promoter, designated phsto, permits in vitro transcription of rnas devoid of vector-derived nucleotides. this vector has been characterized for relative transcriptional activity using constructs which alter the conserved nucleotides extending beyond the sp6 transcriptional initiation site. sp6 polymerase efficiently transcribes cdna inserts which contain a guanosine (g) nucleotide at position +1 relative to the sp6 promoter; however, inserts with an ade ...	1988	3260027
evidence that the 5'-untranslated leader of mrna affects the requirement for wheat germ initiation factors 4a, 4f, and 4g.	the efficiency of translation of alfalfa mosaic virus (amv) rna 4, barley alpha-amylase (b alpha a) mrna, and two chimeric mrnas, amv 4-b alpha a and b alpha a-amv 4 (in which the 5' leader sequences of the two mrnas were interchanged), was measured in an s30 extract from wheat germ and a fractionated system from wheat germ in which translation could be made dependent upon initiation factor (eif) 3, 4a, 4f, or 4g. in the s30 system, amv rna 4 and the chimeric mrna amv 4-b alpha a are translated ...	1988	3260235
selective inhibition of proteins synthesized from different mrna species in reticulocyte lysates containing l-pyrroline-5-carboxylic acid.	l-pyrroline-5-carboxylic acid is a naturally occurring nonprotein amino acid present in human plasma that changes concentrations with diet. l-pyrroline-5-carboxylic acid inhibited net synthesis of globin in untreated reticulocyte lysates in a dose dependent manner. this inhibition was greater than that observed with equimolar gssg or nadp+ and was prevented by a nadph generating system. l-pyrroline-5-carboxylic acid also inhibited net synthesis of proteins from brome mosaic and alfalfa mosaic vi ...	1988	2827672
expression of alfalfa mosaic virus cdna1 and 2 in transgenic tobacco plants.	chimeric genes composed of dna complementary to alfalfa mosaic virus (aimv) rnas 1 or 2, the camv 35 s promoter, and the nos polyadenylation signal were transferred to the genome of nicotiana tabacum cv. samsun nn by means of the agrobacterium tumefaciens transformation system. transformants contained intact copies of the viral genes and accumulated transcripts of approximately the size predicted from the cloning procedure. using antisera raised against synthetic peptides corresponding to the c- ...	1988	3354206
pharmacokinetics and chemotherapeutic efficacy of adriamycin encapsulated in immunoliposomes against avian myeloblastosis virus infection.	immunoliposomes were prepared using rabbit anti-amv gp80 igg for the targeted chemotherapy of avian myeloblastosis virus infection. adriamycin was encapsulated into immunoliposomes and used for in vivo studies. comparative pharmacokinetics of free drug, drug encapsulated in free liposomes and of drug encapsulated in immunoliposomes in the virus-infected cells revealed that (i) the drug encapsulated in liposomes was cleared from the plasma slowly, and (ii) the drug encapsulated in immunoliposomes ...	1988	3366852
transgenic tobacco expressing tobacco streak virus or mutated alfalfa mosaic virus coat protein does not cross-protect against alfalfa mosaic virus infection.	transgenic tobacco plants expressing the coat protein (cp) genes of tobacco streak virus (tsv) and alfalfa mosaic virus (aimv) were used in studies on cross-protection and genome activation. plants expressing the tsv cp gene were highly resistant to infection with tsv nucleoproteins but were susceptible to infection with aimv nucleoproteins. moreover, these plants could be infected with a mixture of aimv rnas 1, 2, and 3 in contrast to the nontransformed control plants. this demonstrates that th ...	1988	3369086
further implications for the evolutionary relationships between tripartite plant viruses based on cucumber mosaic virus rna 3.	the nucleotide sequence of the rna 3 of the q-strain of cucumber mosaic virus (q-cmv) has been reinvestigated and supporting partial amino acid sequence data obtained for the coat protein. corrections to the previously published sequence of rna 3 [a. r. gould and r. h. symons (1982) eur. j. biochem. 126, 217-226] result in changes to the size and composition of the putative 3a and coat proteins. analysis of the nucleotide sequence revealed a 14-nucleotide sequence present in the intercistronic r ...	1988	3388769
the influence of a double-stranded hindrance on dna synthesis performed by dna polymerase alpha, t4 dna polymerase, dna polymerase i (klenow fragment) and amv reverse transcriptase.	the influence of a double-stranded region on dna synthesis performed by a series of dna polymerases on a single-stranded template was studied. two types of double-stranded hindrances were employed: a stable hairpin formed by the template alone and a region formed by the template and an extraneous oligonucleotide complementary to the template. while t4 and calf thymus alpha dna polymerases are strongly arrested at the beginning of either of the two double-stranded hindrances, the klenow fragment ...	1988	2449362
characterization of the cdna synthesized by avian retrovirus reverse transcriptase using 35 s avian myeloblastosis virus rna and an exogenous bovine primer trna.	bovine trna(trp) can be partially hybridized to the avian myeloblastosis virus (amv) 35 s rna at 37 degrees c, in the presence of amv rna-dependent dna polymerase (reverse transcriptase). this template-primer complex is active in the synthesis of viral cdna. the size of the cdna products synthesized in the in vitro reconstituted amv system was determined by urea-polyacrylamide gel electrophoresis using a trna labelled at the 3'-end by yeast trna nucleotidyl transferase. the synthesized cdna has ...	1988	2450786
high resolution structure of the rna duplex [u(u-a)6a]2.	rna is involved in many biological functions, ranging from information storage and transfer to the catalysis of reactions involving both nucleic acids and proteins. previous crystallographic studies on rna oligomeric chains provide only averaged structures or information limited in resolution. the oligomer [u(u-a)6a]2 was chosen for the study of protein-rna interactions in viruses. its size and base composition mimic portions of the genomic rna in alfalfa mosaic virus that bind to the amino term ...	1988	2458530
avian myeloblastosis virus reverse transcriptase is easier to use than the klenow fragment of dna polymerase i for labeling the 3'-end of a dna fragment.	the 3'----5' exonuclease activity of the klenow fragment operates in 3'-end labeling of dna fragments. in the presence of excess deoxyribonucleoside 5'-triphosphates (dntps), the 5'----3' polymerase activity is dominant over the exonuclease activity. however, in the presence of a small amount of dntps, the exonuclease activity removed deoxyribonucleoside 5'-monophosphate (dnmp) incorporated in the 3'-end of a dna strand by the polymerase activity. we found that the radioactivity of incorporated ...	1988	2461116
mechanism of inhibition of reverse transcriptase by quinone antibiotics. ii. dependence on putative quinone pocket on the enzyme molecule.	inhibition of avian myeloblastosis virus (amv) reverse transcriptase by natural and synthetic quinones including antibiotics could be accounted for by an oxidation-reduction reaction. the quinones were shown to function as electron acceptors as revealed by the catalytic oxidation of nadh by clostridium kluyveri diaphorase which was in excellent agreement with enzyme inhibition activity. the kinetics of inhibition of amv reverse transcriptase by three synthetic quinones with different core struct ...	1988	2461354
mapping of a small phosphopeptide at the carboxyterminus of the viral myb protein by monoclonal antibodies.	several myb-specific monoclonal antibodies were produced and their antigen recognition sites characterized using a series of bacterially expressed truncated myb proteins. the monoclonal antibodies were used for analysing the in vivo phosphorylation site of the oncogene protein from avian myeloblastosis virus (amv), p48v-myb. the p48v-myb protein labeled metabolically with [32p]orthophosphate was isolated from the amv-transformed chicken myeloblast cell line bm-2 by immunoaffinity chromatography. ...	1989	2464784
comparative studies of the inhibitory properties of antibiotics on human immunodeficiency virus and avian myeloblastosis virus reverse transcriptases and cellular dna polymerases.	the inhibition of human immunodeficiency virus (hiv) reverse transcriptase by certain antibiotics and related compounds was studied in comparison with that of avian myeloblastosis virus (amv) reverse transcriptase and cellular dna polymerases alpha and beta. in general, compounds that inhibited hiv reverse transcriptase also inhibited amv reverse transcriptase. for example, 10 micrograms/ml of the isoquinoline quinones used in this study inhibited approximately 80% of the activity of reverse tra ...	1989	2466028
use of avian myeloblastosis virus reverse transcriptase at high temperature for sequence analysis of highly structured rna.	avian myeloblastosis virus reverse transcriptase (amv rt) is routinely used in the sequence analysis of rna and dna templates. we review the various methods for dealing with secondary structures that would otherwise result in premature termination or sequence compression. based on our experience in sequencing the 11-kb single-stranded rna genome of lymphocytic choriomeningitis virus, we have found that raising the reaction temperature above 47 degrees c is the simplest way to overcome template s ...	1989	2473018
intrinsic properties of reverse transcriptase in reverse transcription. associated rnase h is essentially regarded as an endonuclease.	the intrinsic properties of reverse transcriptase in reverse transcription were studied using a synthetic, partial ovalbumin mrna with a synthetic dna oligonucleotide annealed to the 3'-end of the rna as a model substrate. with or without concomitant cdna synthesis, the rnase h activity of avian myeloblastosis virus (amv)-reverse transcriptase cleaved the substrate at a site which would leave a hybrid of between 7 and 14 base pairs between the 3' termini of the rna and dna oligonucleotide. varia ...	1989	2478553
inhibition of reverse transcriptases by flavonoids.	selected naturally occurring flavonoids were shown to inhibit three reverse transcriptases (rt): avian myeloblastosis (amv) rt, rous-associated virus-2 (rav-2) rt and maloney murine leukemia virus (mmlv) rt when poly (ra)oligo(dt)12-18 or rabbit globin mrna were used as template. amentoflavone, scutellarein and quercetin were the most active compounds and their effect was concentration-dependent. the enzymes exhibited differential sensitivity to the inhibitory effects of the flavonoids. the comp ...	1989	2480745
a "zinc-finger"-type binding domain in tobacco streak virus coat protein.	tobacco streak virus (tsv) rna and alfalfa mosaic virus (aimv) rna will replicate only if a few copies of their coat proteins are bound to the rna. to understand this phenomenon experiments were performed to find unique features of the tsv and aimv subunits. atomic absorption analysis showed that tsv and aimv contained substantial quantities of zinc in native virions (approximately one zinc atom per four protein subunits in tsv and one zinc atom per two protein subunits in aimv), while other pla ...	1989	2491924
constitutive expression of pathogenesis-related proteins pr-1, grp, and pr-s in tobacco has no effect on virus infection.	samsun nn tobacco cells were transformed with chimeric genes for pathogenesis-related (pr) proteins derived from genomic (pr-1a, grp) or cdna (pr-s) clones under the transcriptional control of the cauliflower mosaic virus 35s promoter. regenerated plants were assayed by rna and protein gel blotting, and plants showing high specific expression of the inserted genes were selected for self-pollination and seed formation. inspection of second generation transformants showed that constitutive express ...	1989	2535503
effects of ph and ionic strength on precipitation of phytopathogenic viruses by polyethylene glycol.	the effects of ionic strength of the solution (changed by varying nacl concentrations or buffer molarity) on the precipitation with polyethylene glycol (peg) 6000 were studied on phytopathogenic viruses of different morphology: the isometric red clover mottle virus (rcmv), rod-shaped tobacco mosaic virus, flexuous potato virus x (pvx) and bacilliform alfalfa mosaic virus. with increasing nacl concentration or buffer molarity up to a certain level (0.1 mol/l), the efficiency of peg precipitation ...	1989	2565676
identification of two translational products for c-myb.	the c-myb gene is the normal cellular homolog of v-myb, the oncogenic component of avian myeloblastosis virus (amv). the c-myb gene has previously been shown to code for a single protein species of about 75 kd. however, accumulating evidence indicates that this gene could code for multiple mrnas as a result of differential splicing. this was first detected in the abpl-2 tumor line and was later shown to occur in normal cells. to test if indeed these differentially spliced mrnas code for a new pr ...	1989	2674850
[synthesis of 2',3',-dideoxy-3'-fluoradenosine and -guanosine, their 5'-triphosphates and a study of 2',3'-dideoxy-3'-fluoronucleoside- 5'-triphosphates as substrates for dna-polymerases].	potential antiviral and antitumour nucleosides, 3'-fluoro-2', 3'-dideoxy-adenosine and -guanosine, have been synthesized by the chemical transglycosylation reaction using 5'-o-acetyl-3'-fluoro-2', 3'-dideoxy-thymidine and -uridine as donors of the carbohydrate fragment and persilylated 6-n-benzoyladenine and 2-n-palmitoylguanine as acceptors, respectively. 5'-triphosphates of 3'-fluoro-2', 3'-dideoxy-thymidine, -cytidine, -adenosine, and -guanosine (dntp(3'f] were synthesized and tested as termi ...	1989	2675851
competitive multiplication of rna3 species of different strains of alfalfa mosaic virus.	competition between rna3 from alfalfa mosaic virus (almv) strain s (rna3-s), strain b (rna3-b) and strain 425l (rna3-l) was studied. the identification of the rna3 species multiplying in infected leaves was possible since the rna3 5' non-coding leader sequences in strains s, b and 425l differ in length. rna3 present in total rna from infected tobacco leaves was detected, and strains were identified from the length of the cdna reverse-transcribed from rna primed with a specific oligonucleotide. i ...	1989	2732703
biological properties of streptonigrin derivatives. iii. in vitro and in vivo antiviral and antitumor activities.	antitumor antibiotic streptonigrin (stn-cooh) is a potent inhibitor of avian myeloblastosis virus (amv) and human immunodeficiency virus reverse transcriptases. the carboxyl group at 2'-position of stn-cooh was modified to give esters, hydrazide, amides and amino acid derivatives for biological studies. against amv reverse transcriptase, the hydrazide, amides and amino acid derivatives showed inhibitory activity, which compared favorably to that of stn-cooh, with the id50 values ranging 2-8 micr ...	1989	2737955
alfalfa mosaic virus temperature-sensitive mutants. v. the nucleotide sequence of tbts 7 rna 3 shows limited nucleotide changes and evidence for heterologous recombination.	nucleotide sequence determination of the coat protein cistron of the alfalfa mosaic virus (aimv) temperature-sensitive mutant, tbts 7 (uv) revealed a small number of point mutations of which only one results in the replacement of an amino acid: the asparagine residue at position 126 is replaced by an aspartate residue. rna transcribed in vitro from a tbts 7 cdna 4 clone directed the production in vitro of a polypeptide which shows the same altered electrophoretic mobility in sds-polyacrylamide g ...	1989	2763460
preparation of soluble, biologically active alfalfa mosaic virus coat protein and its cacl2-induced degradation.	a method for the preparation of soluble protein from five biologically distinct alfalfa mosaic virus (amv) isolates is described. highly purified amv was dissociated with 1 m cacl2 in 10 mm sodium acetate, ph 6.0, and the precipitated rna was removed by centrifugation. the protein was dialysed against 10 mm sodium acetate, ph 6.0, containing 0.1 m cacl2. if the salt concentration was reduced further, proteins from some amv isolates precipitated. proteins prepared by this method were shown to be ...	1989	2778029
host-pathogen interactions : xxxii. a fungal glucan preparation protects nicotianae against infection by viruses.	a glucan preparation obtained from the mycelial walls of the fungus phytophthora megasperma f.sp. glycinea and known as an elicitor of phytoalexins in soybean was shown to be a very efficient inducer of resistance against viruses in tobacco. the glucan preparation protected against mechanically transmitted viral infections on the upper and lower leaf surfaces. whether the glucan preparation was applied by injection, inoculation, or spraying, it protected the plants if applied before, at the same ...	1989	16666737
controlled cell wall regeneration for efficient microinjections of nicotiana tabacum var. carlson protoplasts.	nicotiana tabacum var. carlson protoplast culture conditions were modified to contain a cell wall inhibitor, 2,6-dichlorobenzonitrile, in order to delay cell wall regeneration and to allow efficient nuclear and cytoplasmic microinjections. under modified conditions, the protoplast preparations appeared healthier as compared to the control protoplasts and showed no resistance at all during microinjection. furthermore, the duration of protoplast microinjection was extended for up to 3-4 days. in o ...	1990	24226592
genotype- and promoter-induced variability in transient β-glucuronidase expression in pea protoplasts.	leaf mesophyll protoplasts isolated from pea (pisum sativum l.) genotypes century and pi244253 showed transient expression of β-glucuronidase (gus) when electroporated with plasmid dna containing various promoter-leader sequence constructs driving the gus gene. the optimum conditions for transient expression were: using protoplasts isolated from leaf material that had been kept in the dark for 90 h; electroporating at 250 v and 960 μf; and using 125 μg of calf thymus carrier dna and 75 μ of plas ...	1990	24226370
indirect double antibody sandwich elisa for detecting alfalfa mosaic virus in aphids after short probes on infected plants.	an indirect double antibody sandwich enzyme-linked immunosorbent assay (idas-elisa) system using antibodies elicited in rabbits and chickens is described for the detection of alfalfa mosaic virus (amv). the method is capable of detecting 40 pg of homologous purified amv and was shown to be suitable for detecting the virus in aphids. amv in the order of 150 pg was detected in single aphids. it was shown that a significant proportion of insects could acquire this or higher amounts of virus during ...	1990	2086598
the establishment of rat hybridoma cell lines secreting mcab against strains of potato virus y and analysis of its stability.	the rat splenocytes immunized with potato virus y (pvyn) and ratmyeloma (ir983) were fused by peg (m. w.1450). three kinds of stable hybridoma cell lines secreting specific monoclonal antibodies (mcabs) were derived. one kind of the cell lines producing mcabs reacts to pvyn specifically. another reacts to pvyo specifically. the third one reacts to both of the two strains. tested by the methods of sandwich-elisa and indirect-elisa, all kinds of mcabs did not react to seven plant viruses: tobacco ...	1990	2104212
novel fluorogenic substrates for assaying retroviral proteases by resonance energy transfer.	the 11-kd protease (pr) encoded by the human immunodeficiency virus 1 (hiv-1) is essential for the correct processing of viral polyproteins and the maturation of infectious virus, and is therefore a target for the design of selective acquired immunodeficiency syndrome (aids) therapeutics. to facilitate the identification of novel inhibitors of hiv-1 pr, as well as to permit detailed studies on the enzymology and inhibition of this enzyme, a continuous assay for its activity was developed that wa ...	1990	2106161
differentiation and antigenic characterization of closely related alfalfa mosaic virus strains with monoclonal antibodies.	a panel of 15 mouse monoclonal antibodies (mabs) was raised against five strains of alfalfa mosaic virus (amv) which were closely related antigenically but biologically distinct. a wide diversity of mab specificity was revealed by screening them in three formats of indirect elisa, using native and glutaraldehyde-fixed amv particles as well as isolated coat protein preparations. of these mabs, seven reacted specifically with only one amv strain in at least one elisa format and at least one mab wa ...	1990	2125636
effects of 5' and 3' truncations of the myb gene on the transforming ability of avian myeloblastosis virus (amv).	proviruses based on the avian myeloblastosis virus (amv) have been constructed which code for variations of the c-myb and/or v-myb gene product. these proviruses have been used in a soft colony agar assay to assess the contributions of the 5' and 3' deletions of the v-myb oncogene in the cellular transforming activity of the virus. the results indicate that 3' truncations are an integral part of the gene's mechanism of activation and that the truncations on the 5' end of the gene are important e ...	1990	2158185
proteases from human immunodeficiency virus and avian myeloblastosis virus show distinct specificities in hydrolysis of multidomain protein substrates.	the virally encoded proteases from human immunodeficiency virus (hiv) and avian myeloblastosis virus (amv) have been compared relative to their ability to hydrolyze a variant of the three-domain pseudomonas exotoxin, pe66. this exotoxin derivative, missing domain i and referred to as lyspe40, is made up of a 13-kilodalton nh2-terminal translocation domain ii connected by a segment of 40 amino acids to enzyme domain iii of the toxin, a 23-kilodalton adp-ribosyltransferase. hiv protease hydrolyzes ...	1990	2161935
captan binding to avian myeloblastosis virus reverse transcriptase and its effect on rnase h activity.	the inhibitor captan (n-trichloromethylthio-4-cyclohexen-1,2-dicarboximide) was used to explore the ribonuclease h (rnase h) active site of avian myeloblastosis virus (amv) reverse transcriptase. gel permeation chromatography of purified enzyme showed that [14c]captan bound to the alpha subunit in a ratio of 10:1 and to a 32,000 d polypeptide in a ratio of 4:1. neither the alpha beta nor the beta subunit bound [14c]captan. the binding of 5 of the captan molecules was prevented by preincubating e ...	1990	2166233
translation initiation factor-dependent extracts from saccharomyces cerevisiae.	translation initiation factor 4a- and 4e-dependent extracts were developed from saccharomyces cerevisiae and used to study factor requirements for translation of individual mrnas in vitro. whereas all mrnas tested required eif-4a, mrnas devoid of secondary structure in their 5' untranslated region did not require exogenous eif-4e for translation. the latter included alfalfa mosaic virus rna4, mrna containing the untranslated region of tobacco mosaic virus rna and mrna containing part of the untr ...	1990	2169890
two distinct and frequently mutated regions of retinoblastoma protein are required for binding to sv40 t antigen.	the retinoblastoma susceptibility gene (rb) encodes a phosphoprotein of 110 kd (pp110rb) that forms specific complexes with sv40 t antigen and the transforming proteins of several other dna tumor viruses. interaction with rb is thought to contribute to transformation by these viruses as demonstrated by genetic analyses. to help understand the function of these interactions, the regions of rb that are involved in binding to t have been mapped. an in vitro protein synthesis system capable of produ ...	1990	2189724
proteolytic cleavage of microtubule-associated proteins by retroviral proteinases.	aspartic proteinases from human immunodeficiency virus type 1 (hiv-1) and avian myeloblastosis virus (amv) were found to interfere with microtubule assembly. preincubation of the proteinases with purified brain microtubule proteins (tubulin and microtubule-associated proteins) at low ionic strength (ph 6.8), completely inhibited microtubule assembly. analysis of microtubule proteins after incubation with proteinase showed no effect on tubulin but extensive cleavage of the microtubule-associated ...	1990	2212989
the absence of a m7g cap on beta-globin mrna and alfalfa mosaic virus rna 4 increases the amounts of initiation factor 4f required for translation.	beta-globin mrna and alfalfa mosaic virus (amv) rna 4, two naturally capped mrnas, and satellite tobacco necrosis virus (stnv) rna, a naturally uncapped mrna, were prepared by in vitro transcription with and without a 5' m7g cap structure (m7g(5')ppp(5')n). the translation of the capped and uncapped forms of these mrnas was measured in a crude s30 system and a partially purified system from wheat germ. in the s30 system the uncapped forms of beta-globin mrna and amv rna 4 are much less active (g ...	1990	2246243
the nucleocapsid protein isolated from hiv-1 particles binds zinc and forms retroviral-type zinc fingers.	the role of zinc in retroviral gag protein function has been addressed through the application of high-resolution nuclear magnetic resonance spectroscopy to samples of the nucleocapsid protein (ncp, p7) isolated directly from infectious hiv-1 particles. unlike reports for the ncp from avian myeloblastosis virus (amv) particles [jentoft et al. (1988) proc. natl. acad. sci. u.s.a. 85, 7094], we find that the hiv-1 ncp binds 2 equiv of zinc tightly and stoichiometrically. two-dimensional nmr spectr ...	1990	2261434
similarities between putative transport proteins of plant viruses.	the nucleic acids of many plant viruses encode proteins with one or more of the following properties: an mr of approximately 30,000, localization in the cell wall of the infected plant and a demonstrated role in cell-to-cell transport of infection. a progressive alignment strategy, aligning first those sequences known to be similar, and then aligning the resulting groups of sequences, was used to examine further the relatedness of the amino acid sequences of putative transport proteins of caulim ...	1990	2345362
cis-acting elements involved in replication of alfalfa mosaic virus rnas in vitro.	a dna copy of alfalfa mosaic virus (aimv) rna3 was transcribed in vitro in two different orientations with t7 rna polymerase and the transcripts were used as templates for a virus-specific rna-dependent rna polymerase (rdrp) purified from aimv-infected bean plants. minus-stranded templates were transcribed by the rdrp into subgenomic plus-stranded rna4. a deletion analysis showed that a sequence in minus-strand rna3, located between nucleotides -8 and -55 upstream of the initiation site for rna4 ...	1990	2345958
biologically active transcripts of alfalfa mosaic virus rna3.	transcripts of the bicistronic rna3 of alfalfa mosaic virus were synthesized using the in vitro t7 run-off transcription system. synthetic rna3 containing one additional g nucleotide at the 5' end were found to be infectious when coinoculated with rna1 and rna2 and coat protein.	1990	2358065
[rna-dependent dna-polymerase from avian myeloblastosis virus: effectiveness of interaction with oligothymidylate primers of various length].	optimal conditions for the reaction of polymerization catalyzed by rna-dependent dna-polymerase from amv on poly(a)- and poly(da)-templates with d(pt)n-primers were established. optimal concentrations of the components and ph of the reaction mixtures were found out to differ significantly. dttp was shown to be both a nucleotide substrate and a minimal primer of the polymerization. the km values for d(pt)2-primer (km = 0.11 mm and 0.54 for poly(a) and poly(da)-templates, respectively) and longer ...	1990	1694567
[comparative inhibitory analysis of dna biosynthesis catalyzed by retrovirus reverse transcriptase].	comparative study of dna biosynthesis inhibition, catalyzed by avian myeloblastose virus (amv) reverse transcriptase (rt), human immunodeficiency virus (hiv) recombinant and native rt, has been performed. 3'-azido-2',3'-dideoxythymidine 5'-triphosphate (azttp); 3'-azido-2',3'-dideoxythymidine 5'-methylenephosphonate-diphosphate: 3'-azido-2',3'-dideoxythymidine 5'-phosphate-phosponoacetate; 3'-azido-2',3'-dideoxythymidine 5'-phosphate-dibromomethylenephosphonate; 2',3'-o-isopropylidenecytidine 5' ...	1990	1695849
hybrids between rubella virus and a latent virus of baby hamster kidney cell line bhk21: characterization of rubella virus and type 2 hybrid virus genomes and determination of their physical homology.	the biochemical nature of rubella virus and type 2 hybrid virus, which is a recombinant between rubella virus and a latent retrovirus of bhk21 cells, has been characterized. type 2 hybrid virus carries dna polymerase able to copy exogenous dna. however, disrupted type 2 hybrid virions do not synthesize detectable amounts of dna using the endogenous viral rna or synthetic poly(ra)/oligo(dt) primed as a template. thus, the type 2 hybrid virus dna polymerase has no detectable reverse transcriptase ...	1990	1697423
inhibition of avian myeloblastosis virus reverse transcriptase by diphosphates of acyclic phosphonylmethyl nucleotide analogues.	diphosphates of n-(2-phosphonylmethoxyethyl) derivatives of heterocyclic bases were studied in the endogenous oligo(dt)12-18 primed reaction of reverse transcriptase from detergent-disrupted amv(mav) retrovirions. these diphosphates (analogues of nucleotide 5'-triphosphates) exhibited an inhibitory activity towards reverse transcriptase. this inhibitory activity was dependent on the character of the heterocyclic base and decreased in the order: 2-aminoadenine greater than adenine greater than gu ...	1990	1699492
acyclic nucleotide analogues: synthesis, antiviral activity and inhibitory effects on some cellular and virus-encoded enzymes in vitro.	several n-(s)-(3-hydroxy-2-phosphonylmethoxypropyl) (hpmp) and n-(2-phosphonylmethoxyethyl) (pme) derivatives of purine bases (adenine, guanine, 2-aminoadenine, 3-deazaadenine) and cytosine inhibit the growth of various dna viruses. pme-derivatives (pmea, pmeg and pmedap) are also active against retroviruses. both types of nucleotide analogues undergo phosphorylation by cellular nucleotide kinases to their mono- and diphosphates. the phosphorylation with crude extracts of l-1210 cells is potenti ...	1990	1699493
[the effect of bases noncomplementary to the template on the effectiveness of interaction between primers and avian myeloblastosis virus reverse transcriptase].	the comparison of the km and vmax values for various primers was carried out. the primers were either completely complementary to the poly(a)-template or contained noncomplementary bases in different positions from the 3'-end. an increase of the km and vmax values for primers containing noncomplementary bases was shown. the affinity of the amv-revertase complex with poly(a)-template to d(pt)10 was shown to be higher by a factor of 93, 325, 338, 425, 95 and 15 than to d(pt)9(pc), d[(pt)2pc]3pt, d ...	1990	1701218
effects of 2-chloro-2'-deoxyadenosine 5'-triphosphate on dna synthesis in vitro by purified bacterial and viral dna polymerases.	2-chloro-2'-deoxyadenosine 5'-triphosphate (cldatp) was compared with datp as a substrate for dna synthesis by bacterial and viral dna polymerases in vitro. lengths of chain extension and dna synthesis pause sites were determined by comparison with products generated by dideoxynucleotide sequencing methods on the same end-labeled primer/template duplex after high-resolution polyacrylamide gel electrophoresis. reverse transcriptase (rt) from human immunodeficiency virus (hiv-1) and avian myelobla ...	1991	1703019
polymerization and rnase h activities of the reverse transcriptases from avian myeloblastosis, human immunodeficiency, and moloney murine leukemia viruses are functionally uncoupled.	the functional interaction between the rna-dependent dna polymerase and the rnase h activities of reverse transcriptases (rts) were examined using a 272 nucleotide long plasmid-derived rna transcript primed in a specific location. properties of the avian myeloblastosis virus (amv) rt, the human immunodeficiency virus rt and the moloney murine leukemia virus rt were examined. all three enzymes formed stable complexes with the primer-template with half-lives ranging from about 16 to 41 s. each enz ...	1991	1708386
inhibition of avian myeloblastosis virus reverse transcriptase by heterocyclic quinones: structure-activity correlation.	synthetic heterocyclic quinones (107 samples) consisting of o- and p-quinoline quinones, o-isoquinoline quinones and p-quinoxaline quinones as well as o- and p-naphthoquinones (3 samples) were tested for their inhibitory activities against avian myeloblastosis virus reverse transcriptase (amv-rt) and cytotoxic activities against mouse lymphoblastoma l5178y cells. in general, o-quinoline quinones (i.e., the 5,6-quinolinedione derivatives) are more potent inhibitors of amv-rt than p-quinoline quin ...	1991	1716528
purification and partial characterization of equine infectious anemia virus reverse transcriptase.	previously we raised a rabbit monospecific antibody (c2003) against a synthetic peptide derived from a sequence within the c-terminal portion of the reverse transcriptase (rt) of the human immunodeficiency virus type 1 (hiv-1). this sequence is found to be conserved in the predicted amino acid sequence of a related lentivirus, the equine infectious anemia virus (eiav). it was previously determined that the c2003 antibody could cross-react with native eiav rt and directly inhibit the dna polymera ...	1991	1718086
reverse transcriptase from human immunodeficiency virus: a single template-primer binding site serves two physically separable catalytic functions.	the binding of substrates to recombinant reverse transcriptase from human immunodeficiency virus (hiv) and the natural enzyme from avian myeloblastosis virus (amv) has been examined by analyzing both the ribonuclease h and the rna-dependent dna polymerase activities. with 3'-end-labeled globin mrna hybridized to (dt)15 as the substrate in the ribonuclease h reaction, the enzymes partially deadenylated the mrna in a distributive manner. under these conditions, there was a rapid initial burst foll ...	1991	1718423
effect of glutaraldehyde-fixation on the immunogenicity, particle stability and antigenic reactivity of alfalfa mosaic virus, and the specificity of elicited antibodies.	glutaraldehyde-fixation was shown to stabilize the structural integrity of alfalfa mosaic virus (amv) particles as well as to increase their immunogenicity and antigenic reactivity. the antigenic reactivity of the particles was substantially increased irrespective of whether the antibodies were from animals immunized with native or fixed amv, or preparations of coat protein subunits isolated from the virus. no significant changes in the antigenic specificity of amv particles were detected follow ...	1991	1719013
the development of virus-resistant alfalfa, medicago sativa l.	we have generated more than 100 transgenic alfalfa plants, via agrobacterium-mediated gene transfer, from genotypes selected from five alfalfa cultivars. these plants express the genes for kanamycin resistance and for the coat protein of alfalfa mosaic virus (amv). the strongest expressers accumulated nearly 500 ng coat protein per mg soluble leaf protein. amv inoculation of protoplasts from these strong expressers indicated that they were resistant to infection by amv, while protoplasts from pl ...	1991	1367011
change in phenotype and encapsidated rna segments of an isolate of alfalfa mosaic virus: an influence of host passage.	a local lesion isolate of alfalfa mosaic virus (amv-n20) from lucerne was found to encapsidate two extra rnas in addition to the four major rnas (rna1, -2, -3 and -4). these were resolved by gel electrophoresis both under native conditions and after glyoxal denaturation. the rna with an electrophoretic mobility between that of rnas 2 and 3 was designated rna31, that between rnas 3 and 4 was designated rna3s. sucrose density gradient centrifugation analysis of amv-n20 showed six instead of the no ...	1991	1765766
rapid detection of hog cholera virus in tissues by the polymerase chain reaction.	a rapid method for the detection of hog cholera virus (hcv) in infected tissues, using polymerase chain reaction (pcr) was developed. total rna isolated from hcv-infected tissues was reverse transcribed with amv reverse transcriptase and the resulting complementary dna was amplified by taq dna polymerase in the presence of two hcv-specific primers. the amplified dna fragment was detected by agarose gel electrophoresis. the sensitivity of this method was at 10(4) tcid50 of hcv. the sensitivity in ...	1991	1816255
deletion analysis of cis- and trans-acting elements involved in replication of alfalfa mosaic virus rna 3 in vivo.	dna copies of alfalfa mosaic virus (aimv) rna 3 were transcribed in vitro into rna molecules with deletions in coding and noncoding sequences. the replication of these transcripts was studied in protoplasts from transgenic tobacco plants expressing dna copies of aimv rnas 1 and 2. deletions in the 5'-proximal p3 gene, encoding the putative viral transport function, did not affect replication whereas deletions in the 3'-proximal coat protein gene reduced replication of rna 3 by about 100-fold. se ...	1991	1853568
complementation and recombination between alfalfa mosaic virus rna3 mutants in tobacco plants.	deletions were made in an infectious cdna clone of alfalfa mosaic virus (aimv) rna3 and the replication of rna transcripts of these cdnas was studied in tobacco plants transformed with aimv replicase genes (p12 plants). previously, we found that deletions in the p3 gene did not affect accumulation of rna3 in p12 protoplasts whereas deletions in the coat protein (cp) gene reduced accumulation 100-fold (a. c. van der kuyl, l. neeleman, and j. f. bol, 1991, virology 183, 687-694). in p12 plants del ...	1991	1853571
proto-oncogene expression in avian hematopoietic tissues.	previous findings from this laboratory (kim & baluda, 1988) have shown that the proto-oncogenes ets, fps, mht (raf), myc and rel are expressed in avian myeloblastosis virus (amv)-transformed cells, whereas the myb gene is repressed. in this study five different chicken hematopoietic tissues which contained varying concentrations of target cells for amv transformation were analyzed to determine whether the expression of these proto-oncogenes resulted from, or was altered by, v-myb-induced leukemo ...	1991	1886713
development of an acid-soluble assay for measuring retrovirus integrase 3'-oh terminal nuclease activity.	a quantitative and efficient assay was developed to measure the 3'-oh terminal dna endonuclease activity of the avian myeloblastosis virus (amv) integrase protein. a retroviral-like linearized plasmid containing long terminal repeat (ltr) sequences at its recessed 3'-oh termini was filled in and labeled with the escherichia coli klenow dna polymerase fragment. the 32p-labeled nucleotide was located at the penultimate position. the labeled linearized plasmid or restriction fragments derived from ...	1991	1888032
v-myb transformation of xeroderma pigmentosum human fibroblasts: overexpression of the c-ha-ras oncogene in the transformed cells.	human xeroderma pigmentosum "normal" fibroblasts as16 (xp4 vi) were transformed after transfection with a recombinant v-myb clone. in this clone (pkxa 3457) derived from avian myeloblastosis virus (amv), the expression of the oncogene sequences is driven by the amv u-5 ltr promoter. the transformed cells (askxa), which have integrated a rearranged v-myb oncogene, grow in agar, are not tumorigenic in nude mice, and express a 45-kda v-myb protein. the hmw dna of these cells transform chicken embry ...	1991	1893942
nucleotide sequence of raspberry bushy dwarf virus rna-2: a bicistronic component of a bipartite genome.	northern blot analysis with cdna probes to rna-3 (1 kb) of raspberry bushy dwarf virus (rbdv) revealed extensive sequence homology with rbdv rna-2 (2.2 kb). nucleotide sequencing showed that rna-2 contains two large open reading frames (orfs), of 1074 (5' orf) and 822 (3' orf) bases. the 3' orf is virtually identical in sequence to rna-3, which encodes the mr 30509 (30k) coat protein. the 5' orf encodes an mr 38860 (39k) protein which slightly resembles the 32k protein encoded by rna-3 of alfalf ...	1991	1895055
some observations on the binding properties of alfalfa mosaic virus to polystyrene and its significance to indirect elisa.	the adsorption and retention properties of native (unfixed) and glutaraldehyde-fixed alfalfa mosaic virus (amv) antigens to the polystyrene of elisa plates were studied using [35s]-labelled virus preparations. it was shown that adsorption was a temperature-dependent, relatively slow process which varied between different amv isolates. the amount of virus antigen adsorbed was dependent on the type and ph of the suspending buffer. although native virus antigen adsorbed very efficiently at high ph ...	1991	1902080
role of alfalfa mosaic virus coat protein in regulation of the balance between viral plus and minus strand rna synthesis.	replication of wild type rna 3 of alfalfa mosaic virus (aimv) and mutants with frameshifts in the p3 or coat protein (cp) genes was studied in protoplasts from tobacco plants transformed with dna copies of aimv rnas 1 and 2. accumulation of viral plus and minus strand rnas was monitored with strand-specific probes. a frameshift in the p3 gene did not change the asymmetry in plus/minus strand accumulation observed for the wild type. a frameshift early in the cp gene resulted in a 100-fold reducti ...	1991	1926791
effect of removal of zinc on alfalfa mosaic virus rna-dependent rna polymerase.	the necessity of coat protein for infection of plants by alfalfa mosaic virus (aimv) and other ilarviruses distinguishes this virus group from other plant virus groups. recently, the presence of both a zinc-finger type motif and zinc in aimv coat protein was described [(1989) virology 168, 48-56]. we studied the effect of a zinc chelator on viral rna synthesis. strong inhibition of aimv rna-dependent rna polymerase (rdrp) by ortho-phenanthroline (op) was observed.	1991	1993475
alfalfa mosaic virus rna3 mutants do not replicate in transgenic plants expressing rna3-specific genes.	the rna3 of alfalfa mosaic virus (aimv) encodes the p3 protein and the viral coat protein (cp). rna3 molecules transcribed in vitro replicated in protoplasts and plants when inoculated in mixtures with aimv rna1, rna2 and cp. transcripts with a deletion or inversion in the p3 gene replicated well in protoplasts but not in transgenic plants transformed with the p3 gene. transgenic plants expressing the cp gene became infected after inoculation with a mixture of rna1, rna2 and wild-type rna3 trans ...	1991	1993869
replication of an incomplete alfalfa mosaic virus genome in plants transformed with viral replicase genes.	rnas 1 and 2 of alfalfa mosaic virus (aimv) encode proteins p1 and p2, respectively, both of which have a putative role in viral rna replication. tobacco plants were transformed with dna copies of rna1 (p1-plants), rna2 (p2-plants) or a combination of these two cdnas (p12-plants). all transgenic plants were susceptible to infection with the complete aimv genome (rnas 1, 2, and 3). inoculation with incomplete mixtures of aimv rnas showed that the p1-plants were able to replicate rnas 2 and 3, tha ...	1991	2014633
role of alfalfa mosaic virus coat protein gene in symptom formation.	on samsun nn tobacco plants strains 425 and ysmv of alfalfa mosaic virus (aimv) cause mild chlorosis and local necrotic lesions, respectively. dna copies of rna3 of both strains were transcribed in vitro into infectious rna molecules. when the 425 and ysmv transcripts were inoculated to tobacco plants transformed with dna copies of aimv rnas 1 and 2, they induced symptoms indistinguishable from those of the corresponding parent strains. exchange of restriction fragments between the infectious cl ...	1991	2014643
analysis of the protein composition of alfalfa mosaic virus rna-dependent rna polymerase.	rna-dependent rna polymerase (rdrp) was solubilized and purified from cellular membranes isolated from alfalfa mosaic virus (aimv)-infected tobacco by employing a procedure recently described for brome mosaic virus rdrp [r. quadt and e.m.j. jaspars, 1990, virology 178, 189-194]. the purified aimv rdrp is completely dependent on added template rnas and exhibits a high degree of template specificity. analysis of the protein composition of aimv rdrp showed that aimv-encoded proteins p1 and p2 and t ...	1991	2024468
universal promoter for gene expression without cloning: expression-pcr.	we present a rapid and simple system called expression-pcr (e-pcr) for in vitro synthesis of functional protein from genomic or plasmid dna. a universal promoter was developed containing an untranslated leader sequence from alfalfa mosaic virus directly downstream from the t7 bacteriophage promoter. when this universal promoter is spliced to a dna segment, it produces a suitable template for in vitro transcription and translation. the dna to be expressed is first amplified by the pcr using a 5'- ...	1991	2064773
cdna cloning of a homeobox-containing gene expressed in avian myeloblastic virus-transformed chicken monoblastic leukaemia cells.	by combining the polymerase chain reaction and differential library screening, a cdna for an mrna expressed in chicken avian myeloblastosis virus (amv)-transformed monoblasts was isolated. this mrna is not expressed in erythroblast or t-lymphoblast cell lines. induced differentiation of the cells of the amv-transformed bm2 line was associated with reduced levels of this transcript. the predicted protein product of chox m was a homeodomain factor similar to murine hox-4.3.	1991	1674560
diverse groups of plant rna and dna viruses share related movement proteins that may possess chaperone-like activity.	amino acid sequences of plant virus proteins mediating cell-to-cell movement were compared to each other and to protein sequences in databases. two families of movement proteins have been identified, the members of which show statistically significant sequence similarity. the first, larger family (i) encompasses the movement proteins of tobamo-, tobra-, caulimo- and comoviruses, apple chlorotic leaf spot virus (aclsv) and geminiviruses with bipartite genomes. thus this family includes viruses wh ...	1991	1684985
relationship of 2',3'-cyclic nucleotide 3'-phosphohydrolase activity of large enveloped rna viruses to host cell activity.	purified virions of the large rna viruses show 2',3'-cyclic nucleotide 3'-phosphohydrolase (3'-cnpase) activity. the 3'-cnpase activity is virion-associated and stimulated by their treatment with nonionic detergents. cytopathic viruses such as influenza a2 (singapore/57), ndv, and vsv showed the specific activity of a virion-associated 3'-cnpase equal to or lower than the specific activity of host cell enzyme. retroviruses are an example of extreme relationship of 3'-cnpase to virion. with the a ...	1991	1688073
the second amino acid of alfalfa mosaic virus coat protein is critical for coat protein-mediated protection.	transgenic plants expressing the coat protein (cp) of alfalfa mosaic virus (aimv) are resistant to infection by aimv. a mutation was introduced into the second amino acid of the cdna for the cp of aimv. three different transgenic tobacco lines expressing the mutant cp and two different transgenic tobacco lines expressing the wild-type cp at similar levels were challenged with aimv virions and viral rna. whereas the lines expressing the wild-type cp were highly resistant to infection by aimv viri ...	1991	11607167
reverse transcriptase inhibits taq polymerase activity.	detection of viral rna by polymerase chain reaction (pcr) requires the prior reverse transcription of the viral rna. in order to minimise the number of manual manipulations required for processing large numbers of samples, we attempted to design a system whereby all the reagents required for both reverse transcription and amplification can be added to one tube and a single, non-interrupted thermal cycling program performed. whilst attempting to set up such a one-tube system with taq polymerase ( ...	1992	1374554
comparison of hiv-1 and avian myeloblastosis virus reverse transcriptase fidelity on rna and dna templates.	a comparison of the fidelity of reverse transcriptases (rt) from human immunodeficiency virus (hiv-1) and avian myeloblastosis virus (amv) is made using rna and dna primer-template molecules in vitro. selected template target sites containing either uracil or thymine are used to measure nucleotide insertion fidelities and to compare the efficiency of extending mismatched nucleotides at primer 3'-termini. hiv-1 reverse transcriptase is observed to incorporate as many as three consecutive mismatch ...	1992	1375233
binding of rna by the alfalfa mosaic virus movement protein is biphasic.	the movement protein of alfalfa mosaic virus was expressed in escherichia coli and purified by cation exchange chromatography. the purified protein bound single-stranded rna cooperatively in a biphasic manner. at protein saturation, rna/protein complexes (designated 'primary complexes') were detected by a nitrocellulose-retention assay within 1 min of mixing, both at 4 and 22 degrees c. in contrast, an incubation of 30 min at 22 degrees c was necessary to obtain electrophoretically retarded comp ...	1992	1380465
exogenous primer-independent cdna synthesis with commercial reverse transcriptase preparations on plant virus rna templates.	upon reverse transcription and cloning manipulations with virion rnas of several plant viruses, namely beet yellows virus, brome mosaic virus, and potato virus x, we came across a significant background synthesis of cdna on the virion rna template in vitro independent of exogenous primers added. when tested with beet yellow virus rna template, several commercial preparations of avian myeloblastosis virus (amv) reverse transcriptase showed the background activity monitored by the [alpha-32p]dntp ...	1992	1381874
cross-reacting and heterospecific monoclonal antibodies produced against arabis mosaic nepovirus.	monoclonal antibodies (mabs) were produced against arabis mosaic nepovirus (amv). a hybridoma screening procedure was applied which involved the testing of culture supernatants, before the hybridomas were cloned to single cell lines, for their reaction with eight nepoviruses [amv, cherry leafroll virus (clrv), grapevine fanleaf virus (gflv), peach rosette mosaic virus, raspberry ringspot virus (rrsv), tobacco ringspot virus, tomato black ring virus (tbrv) and tomato ringspot virus]. in addition ...	1992	1402798
protein truncation is not required for c-myb proto-oncogene activity in neuroretina cells.	the v-myb oncogene of avian myeloblastosis virus (amv) differs from its normal cellular counterpart by a truncation at both its amino and carboxyl termini and by a substitution of 11 amino acid residues. we had previously shown that v-myb-containing amv, in the presence of basic fibroblast growth factor, transformed chicken neuroretina (cnr) cells. to understand the mechanism of c-myb activation, we have tested whether avian retroviruses that express the full-length c-myb are also active on cnr ...	1992	1404616
[the technology for isolating the avian myeloblastosis virus in high titers from leukosis-free chicks].	in order to enhance the outcome of high-quality reverse transcriptase enzyme, an efficient biotechnology was developed of accumulating and isolating the avian myeloblastosis virus (amv) in high titres from blood plasma of leukosis-free chickens. when commercial chickens are infected in most sensitive one-day age, the virus titre does not exceed the value of 10(12) particles per 1 ml of plasma. we used 3-4-day old leukosis free chickens and achieved a stable average titre of the virus of 5.10(12) ...	1992	1430580
the nucleotide sequence of rna-1 of raspberry bushy dwarf virus.	raspberry bushy dwarf virus (rbdv) has isometric, 33 nm diameter particles and a bipartite rna genome. sequencing of the larger component (rna-1) showed that it consists of 5449 nucleotides and contains one large open reading frame encoding a putative translation product with a calculated m(r) of 190,000. comparisons of this polypeptide with non-structural proteins of other plant viruses revealed significant homologies with those of alfalfa mosaic virus (almv), brome mosaic virus (bmv), cucumber ...	1992	1469359
identification of genes differentially expressed in two types of v-myb-transformed avian myelomonocytic cells.	in an earlier study we found that different forms of the v-myb oncogene transform myeloid cells which resemble either monoblasts [when v-myb of avian myeloblastosis virus (amv) was used] or promyelocytes [when a point mutant in v-myb of amv was used; introna, m., golay, j., frampton j., nakano, t., ness, s.a. & graf, t. (1990). cell, 63, 1287-1297]. in the present study we have searched for genes expressed in amv mutant-transformed promyelocytes that are not expressed in amv-transformed monoblas ...	1992	1549365
transforming potential of truncated v-myb and stimulation of replication by gag-myb fusion products.	we have previously reported that truncated forms of the v-myb oncogene of avian myeloblastosis virus (amv) are expressed in transformed chicken embryo fibroblasts (cef). in this paper, we show that deletion mutants encoding v-myb products altered in either the dna-binding or the negative regulatory domains are able to induce cef transformation. in addition, we report that recombinant plasmids expressing gag-myb fusion proteins are maintained as extrachromosomal forms in transfected cells. this o ...	1992	1549366
nucleic acid-binding properties of the alfalfa mosaic virus movement protein produced in yeast.	the movement protein of alfalfa mosaic virus (p3) was purified from yeasts transformed with an expression vector containing the p3 gene. its nucleic acid-binding properties were tested by electrophoretic retardation, nitrocellulose retention, and rna-protein cross-linking. the recombinant protein had a higher affinity for single-stranded rna and dna than for double-stranded nucleic acids. each nucleic acid molecule bound several protein molecules without sequence specificity. the binding was 80% ...	1992	1585656
extension of the dna binding consensus of the chicken c-myb and v-myb proteins.	the chicken c-myb gene and the v-myb oncogene transduced by avian myeloblastosis virus (amv) encode dna binding transcription activators. the dna binding domain of amv v-myb displays a number of amino acid changes relative to c-myb; v-myb proteins in which one or more of three crucial residues in the dna binding domain are mutated to resemble the c-myb sequence display altered transformation phenotypes. in order to establish whether the spectrum of dna binding sites which amv v-myb can recognise ...	1992	1620600