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At least 811 records · Page 45Linked to original sources
PubMed1977

Comparison of interferon-inducing activities and antiviral effects of tobacco mosaic virus, tilorone and sodium nucleinate.

Endogenous interferon was produced in animals in response to the administration of tobacco mosaic virus (TMV), tilorone and sodium nucleinate. The relationship between interferon production and the kind of inducer and the route of its administration was studied. TMV was completely innocuous for Macaca rhesus monkeys and mice and caused no untoward effects in humans upon peroral administration. TMV, tilorone and sodium nucleinate given per os exerted a marked protective effect in mice against tick-borne encephalitis, eastern and western equine encephalomyelitis and influenza virus infections.

Administration, Oral↗
PubMed1990

Capping of tobacco mosaic virus RNA. Analysis of viral-coded guanylyltransferase-like activity.

The 5' end of tobacco mosaic virus (TMV) genomic RNA is capped with 7-methylguanosine. A virus-coded polypeptide with guanylyltransferase activity has been investigated. This enzyme is responsible for forming the 5'----5' linkage of guanosine 5'-monophosphate to the 5'-diphosphate of an acceptor RNA, thereby forming the cap. A critical step in the mechanism for cap formation in the eukaryotic nucleus is for guanylyltransferase to bind covalently to guanosine 5'-monophosphate with the hydrolysis of pyrophosphate when guanosine 5'-triphosphate is the substrate. The TMV 126-kilodalton protein, which is most probably a component of the TMV replicase, was found to have this activity. The mechanism of this reaction has been characterized biochemically.

Binding, Competitive↗
PubMed1990

[A telangiectatic clinical variant of mastocytosis].

Six cases of telangiectatic clinical variant of mastocytosis (TMV) are reported. Patients' age varied from 33 to 62, there were 2 men and 4 women. A number of clinical features of TMV were detected in the course of follow-up: a generalized type of the skin process; abundant maculopapular eruptions colored brownish, sometimes with a cyanotic shade, liable to fuse and form diffuse foci of involvement; development of telangiectasias on the surface of these eruptions; symptoms of elevated blood histamin levels, i.e. regular blood congestion, enhanced itching, tachycardia, gastrointestinal events, etc.; systemic mastocytosis (3 of the 6 patients developed lymphadenopathy and hepatomegaly). The detected features of the condition permit considering TMV as an individual clinical variety of mastocytosis.

Adrenal Cortex Hormones↗
PubMed1989

Lung mucociliary transport in asymptomatic asthma: effects of inhaled histamine.

Bronchial mucociliary clearance (CB) and tracheal mucus velocity (TMV) were measured during the course of repeated inhalations of histamine in six subjects with asthma who had no symptoms in a double-blind, crossover study with a radioaerosol technique. Subjects inhaled a technetium 99m-labeled ferric oxide aerosol with an aerodynamic diameter of approximately 8 microns. CB was recorded for 2.5 hours with a gamma camera, and TMV measured with a multidetector probe situated over the extrathoracic trachea. Histamine was administered repeatedly in concentrations previously shown to produce a 20% fall in forced expired volume in 1 second and at intervals allowing 90% recovery of pulmonary function. Histamine produced a 28% increase in CB (p less than 0.001, analysis of variance) and an 87% increase in TMV (p less than 0.001, analysis of variance) above control values, which was not significantly different from that previously observed in normal subjects receiving significantly higher concentrations of histamine. We conclude that histamine stimulates the mucus transport mechanism in subjects with asthma and that there is a relative hypersensitivity to histamine when these subjects are compared with normal subjects.

Administration, Inhalation↗
PubMed1988

Tobacco mosaic virus infection stimulates the phosphorylation of a plant protein associated with double-stranded RNA-dependent protein kinase activity.

The influence of tobacco mosaic virus (TMV) infection on nucleotide binding and phosphorylation of an Mr 68,000 host-encoded protein (p68) was examined. The phosphorylation of p68 in homogenates from TMV-infected tissues was 4-fold greater than in homogenates from mock inoculated tissues. Phosphorylation of p68 in extracts from mock inoculated tissues was enhanced by the addition of double-stranded (ds) RNA. Nucleotide photoaffinity labeling experiments indicate that p68 contains an ATP binding site with characteristics consistent with protein kinase activity. Antiserum raised against a dsRNA-dependent protein kinase activity. Antiserum raised against a dsRNA-dependent protein kinase from interferon-treated human cells immunoprecipitated p68 from extracts of TMV-infected tissue, and p68-containing immunocomplexes catalyzed the phosphorylation of endogenous p68. These data suggest that p68 may be an autophosphorylating, dsRNA-dependent protein kinase involved in viral pathogenesis. Based upon analogous functions demonstrated for dsRNA-dependent protein kinases in mammalian systems, p68 may have a role in the regulation of protein synthesis and viral replication in infected cells.

Electrophoresis, Polyacrylamide Gel↗
PubMed1987

[Difference in the mechanism of self-assembly in vitro in tobacco mosaic virus and potato virus X].

The effects of 254 nm UV-irradiation of tobacco mosaic virus (TMV) and potato virus X (PVX) RNA preparations on the RNA ability to self-assembly in vitro with the viral coat proteins were studied. It was found that while TMV RNA ability to assemble with the homologous protein is rapidly inactivated by the UV-irradiation, PVX RNA ability to be encapsidated by the PVX coat protein is quite resistant to the irradiation. More than that, the irradiation of TMV RNA with the dose strongly inhibiting its assembly with the homologous protein, did not result in any significant inhibition of this RNA ability to be coated with the PVX protein. The results testify to the profound differences in the mechanisms of RNA-protein interactions in the processes of self-assembly in vitro of tobamoviruses and potexviruses.

Capsid Proteins↗
PubMed1985

Photoaffinity labeling of a viral induced protein from tobacco. Characterization of nucleotide-binding properties.

We have used the photoaffinity analogs 8-azidoadenosine 5'-triphosphate (8-N3ATP) and 8-azidoguanosine 5'-triphosphate (8-N3GTP) to investigate the relationship between a viral induced protein (Mr = 120,000) in tobacco mosaic virus (TMV)-infected tobacco and the TMV-induced RNA-dependent RNA polymerase activity. When the radioactive analogs [gamma-32P]8-N3ATP and [gamma-32P]8-N3GTP were incubated with the tobacco tissue homogenate from TMV-infected plants, incorporation of label occurred into the viral induced protein in the presence of UV light. The incorporation was found to be totally dependent on UV-illumination and greatly enhanced by Mg2+. Saturation of photoincorporated label indicates an apparent Kd of 16 microM (+/- 3 microM) and 12 microM (+/- 3 microM) for 8-N3ATP and 8-N3GTP, respectively. Protection against photolabeling by [gamma-32P]8-N3ATP and [gamma-32P]8-N3GTP with various nonradioactive nucleotides and nucleosides suggests that the photolabeled site is protected best by nucleoside triphosphates. At 200 microM both deoxyribonucleoside triphosphates and ribonucleoside triphosphates were very effective at protecting the site from photolabeling. These data suggest that the photolabeled protein may be part of an RNA-dependent RNA polymerase. The utility of nucleotide photoaffinity analogs as a method to study viral induced nucleotide-binding proteins is discussed.

Adenosine Triphosphate↗
PubMedDate not supplied

[Optical rotatory dispersion by 5 viruses of the tobacco mosaic virus group and their components].

Optical rotatory dispersion (ORD) spectra in 250 to 350 nm region were measured for preparations of five TMV-like viruses (TMV vulgare, HR and U2 strains of TMV dolihosenation mosaic virus and cucumber virus 4) and also for RNA and protein preparations of these viruses. The data obtained testify against the possibility that the double peak with maxima at 286 and 293 nm observed in ORD of all the five viruses is due to interaction of tryptophan residues in virus coat protein with the RNA of the virul particle. The spectra of intravirus RNA of the five viruses, calculated as the difference between ORD of the intact virus and of its coat protein, were found to differ significantly from each other and from ORD of free RNA. ORD spectra of hybrid viruses, reconstituted from RNA of one virus and coat protein of another, proved to be identical to the ORD of the virus, whose protein was used in reconstitution. We suppose that the difference in ORD of the intravirus RNA of the five viruses reflect differences of RNA-protein interactions in them.

Chemical Phenomena↗
PubMedDate not supplied

[Virus and plant-host interrelationships in the presence of rifamycin].

The effect of rifamycine on the infectivity and accumulation in tissues of potato X-virus (PXV) and tobacco mosaic virus (TMV) in local and systemic infections of plants was studied. High concentrations of rifamycine (50--100 microgram/ml) were found to inhibit and low (2 microgram/ml) to stimulate the infectivity of the viruses. Rifamycine reduced accumulation of PXV in isolated leaves of thornapple and growth of necrotic lesions caused by TMV on tobacco leaves. The effectiveness of the antibiotic depends on its concentration, method and time of its use and the kind of the experimental system. The activity of rifamycine towards the induced tobacco resistance to reinfection with TMV was found to be insignificant.

Dose-Response Relationship, Drug↗
PubMedDate not supplied

[Synthesis of virus-specific products following introduction of tobacco mosaic virus RNA pereparations and the native virus into acetabularia].

The possibility to synthesize the viral-specific products after microinjection of Tobacco mosaic virus (TMV) preparations and the TMV RNA into the single-celled seaweed Acetabularia was studied. The accumulation of the newly synthesized protein and double-stranded RNA 24 hours after injection of TMV RNA and native virus preparations was demonstrated by immunological and immunofluorescent methods. The virus titer sharply dropped 3--4 hours after introduction into Acetabularia and in 48 hours it reached a maximum level. The presented data showed the possibility of TMW RNA replication and translation involving formation of viral-specific proteins and the production of a virus of full value in the Acetabularia cell.

Acetabularia↗
PubMed1986

Influence of local structure on the location of antigenic determinants in tobacco mosaic virus protein.

Early work on protein antigenicity led to the common belief that proteins possess a finite number of antigenic determinants located in accessible regions of the molecule's surface. This view is now changing. As a result of extensive studies, seven continuous epitopes have been located on tobacco mosaic virus (TMV) protein by measuring the antigenic activity of short peptides with anti-protein antibodies. The structure of the viral protein has been refined in Cambridge, enabling the Strasbourg workers to correlate the position of these epitopes with regions of high segmental mobility in the protein. Surface accessibility is not a sufficient condition for antigenicity, because six short peptides corresponding to accessible regions of the protein possess no antigenic activity. Recent work in Strasbourg shows that when longer peptides of TMV protein are used, more antigenic determinants are found and these lie in more structured regions of the protein (e.g. helices). In these cases the longer peptide may be folding up in solution to mimic part of the native structure.

Antigens, Viral↗
PubMed2002

Multitrophic interactions of the silverleaf whitefly, host plants, competing herbivores, and phytopathogens.

Our laboratory found that silverleaf whitefly (SLW; Bemisia argentifolii Bellows & Perring) feeding alters host plant physiology and chemistry. The SLW induces a number of host plant defenses, including pathogenesis-related (PR) protein accumulation (e.g., chitinases, beta-1,3-glucanases, peroxidases, chitosanases, etc.). Induction of the PR proteins by SLW feeding occurs in various plant species and varieties. The extent and type of induction is dependent on a number of factors that include host plant growing conditions, the length of time the host plant is exposed to SLW feeding, the plant variety, and SLW population densities. The appearance of PR proteins correlates well with reduced infestations of conspecific insect herbivore competitors. Greenhouse and field experiments in which herbivore competitors (cabbage looper, Trichoplusia ni; leaf miner, Liromyza trifolii) were placed on plants previously exposed to SLW feeding demonstrated behavioral differences (oviposition, feeding preferences) and reduced survival rates and development times of these insects. The interaction was asymmetrical, i.e., SLW infestations of plants previously exposed to leaf miners had little or no effect on SLW behavior (oviposition). Induction of plant-defensive proteins by SLW feeding was both local (at the feeding site) and systemic (uninfested leaves distant to the feeding site). There are interactions between diseases such as tomato mottle virus (ToMoV; a geminivirus) and the host plant and SLW. PR proteins were induced in tomato plants infected with ToMoV much as they were via non-viruliferous SLW feeding. The presence of ToMoV in tomato plants significantly increased the number of eggs produced by SLW females. Experiments using tomato plants, powdery mildew (PM), and tobacco mosaic virus (TMV) show that whitefly infestations can affect plant pathogen relationships but the effects vary among pathogen types. Enzyme analyses prior to pathogen inoculation showed that whitefly treatment significantly increased the activities of foliar chitinase and peroxidase. Evaluation of pathogen growth 3 weeks after inoculation showed that whitefly feeding significantly reduced the incidence of PM. However, TMV levels evaluated by ELISA were not significantly affected by whitefly feeding. Six weeks after inoculation with pathogens, the chitinase and peroxidase activities were still elevated in plants initially fed on by whiteflies but continuing pathogen infection had no effect on these enzymes. The possibility that geminivirus infection and/or SLW infestations isolate the host plant for the selected reproduction of the virus and the insect is discussed. Multitrophic cascade effects may contribute to the successful eruptive appearance of SLW on various crops, ranking them as a major pest. They may explain the general observation that when SLW infest a host plant there are few if any competing insect herbivores and pathogens found in the host. However, the results indicate that certain SLW-virus relationships could be mutualistic.

Animals↗
PubMed1975

Production of plant virus inhibitor by Phytolacca americana suspension culture.

The inhibitory activity of tobacco mosaic virus (TMV) infection was assayed with the extracts of various callus tissues derived from the intact plants. Phytolacca americana callus was selected as a producer of the virus inhibitor and its cultural conditions in suspension were examined for cell growth and the inhibitor production. A modified liquid medium containing twofold concentrations of all components in that of Murashige and Skoog plus2,4-D (1.0 mg/liter) and sucrose (6%), but without any vitamins and glycine was chosen for production of higher levels of the inhibitor. TMV infections in tobacco, bean, and tomato plants were markedly inhibited by the introduction of the disrupted whole broth of suspension cultured P. americana.

Antiviral Agents↗
PubMed1975

Cell surface immunoglobulin. XII. Localization of immunoglobulin on murine lymphocytes by scanning immunoelectromicroscopy.

The localization of immunoglobulin (Ig) on the surface of murine splenic lymphocytes has been studied with the scanning electron microscope (SEM), using a rabbit F(ab')2 hybrid antibody directed against mouse Ig and tobacco mosaic virus (TMV) with TMV as a morphological marker. 35% of spleen cells and 3% of thymus cells were labeled by this method. Labeled cells were usually small lymphocytes with moderate numbers of microvilli. The Ig molecules were randomly distributed on the lymphocyte surface, appearing on microvilli as well as on the smooth surface of the cell.

Animals↗
PubMed1984

The three-dimensional folding of the tRNA-like structure of tobacco mosaic virus RNA. A new building principle applied twice.

The structure of the tRNA-like 3' terminus of tobacco mosaic virus (TMV) RNA has been studied. A 3' -terminal fragment possessing the tRNA-like properties was probed with chemical modification and enzymatic digestions. A model of the secondary structure is proposed for the last 105 nucleotides. The corresponding region of other tobamoviral RNAs can be folded in an identical secondary structure. A three-dimensional model for the tRNA-like structure is given which is compared with those proposed earlier for the tRNA-like 3' termini of turnip yellow mosaic virus (TYMV) RNA and brome mosaic virus (BMV) RNA. A new building principle which we discovered previously by studying the latter RNAs appears to be applied twice in the tRNA-like structure of TMV RNA. The determination of the minimal length requirement for recognition of CTP, ATP:tRNA nucleotidyl-transferase reveals a size of 100 nucleotides in agreement with the models proposed.

Journal Article↗
PubMed1986

Dramatic events in ciliate evolution: alteration of UAA and UAG termination codons to glutamine codons due to anticodon mutations in two Tetrahymena tRNAs.

The three major glutamine tRNAs of Tetrahymena thermophila were isolated and their nucleotide sequences determined by post-labeling techniques. Two of these tRNAs show unusual codon recognition: a previously isolated tRNA(UmUA) and a second species with CUA in the anticodon (tRNA(CUA)). These two tRNAs recognize two of the three termination codons on natural mRNAs in a reticulocyte system. tRNA(UmUA) reads the UAA codon of alpha-globin mRNA and the UAG codon of tobacco mosaic virus (TMV) RNA, whereas tRNA(CUA) recognizes only UAG. This indicates that Tetrahymena uses UAA and UAG as glutamine codons and that UGA may be the only functional termination codon. A notable feature of these two tRNAs is their unusually strong readthrough efficiency, e.g. purified tRNA(CUA) achieves complete readthrough over the UAG stop codon of TMV RNA. The third major tRNA of Tetrahymena has a UmUG anticodon and presumably reads the two normal glutamine codons CAA and CAG. The sequence homology between tRNA(UmUG) and tRNA(UmUA) is 81%, whereas that between tRNA(CUA) and tRNA(UmUA) is 95%, indicating that the two unusual tRNAs evolved from the normal tRNA early in ciliate evolution. Possible events leading to an altered genetic code in ciliates are discussed.

Journal Article↗
PubMed1988

Two concomitant base substitutions in the putative replicase genes of tobacco mosaic virus confer the ability to overcome the effects of a tomato resistance gene, Tm-1.

A resistance-breaking strain of tobacco mosaic virus (TMV), Ltal, is able to multiply in tomatoes with the Tm-1 gene, unlike its parent strain, L. Comparison of the genomic sequences of L and Lta1 revealed two base substitutions resulting in amino acid changes in the 130 and 180 kd proteins: Gln-979 --> Glu and His-984 --> Tyr. To clarify their involvement in the resistance-breaking property of Lta1, the two substitions were introduced into L by an in vitro transcription system to generate a mutant strain, T1. T1 multiplied in Tm-1/Tm-1 tomatoes with symptoms as did Lta1. Two additional mutant strains were constructed, each of which had one base substitution which caused a His-984 --> Tyr change (T2) or a Gln-979 --> Glu change (T3). T3 multiplied in tomato plants and protoplasts with the Tm-1 gene, indicating that the single base substitution is sufficient to overcome the resistance. T2 also multiplied, but its multiplication was greatly decreased. Although no sequence changes were detected in any progeny viruses recovered from plants without the Tm-1 gene, progeny viruses recovered from T2- or T3- inoculated Tm-1/Tm-1 tomatoes contained in most cases viruses with additional second base substitutions. They caused amino acid changes near the mutagenized residues, suggesting that the ability of T3 to overcome the resistance is not the same as that of Lta1. Sequencing of the genomic RNAs of other independently isolated resistance-breaking strains revealed the same two base substitutions found in the Lta1 RNA. These observations suggest that the two concomitant base substitutions, and possibly also the resulting amino acid changes, guarantee successful replication of these TMV strains in tomatoes containing the Tm-1 gene. A strong correlation was found between the ability to overcome the resistance and a decrease in local net charge, suggesting the involvement of an electrostatic interaction between the viral 130 and 180 kd proteins and a putative host resistance factor.

Journal Article↗
PubMed1992

Characterization of a putative calcium-binding site in tobacco mosaic virus.

Lead has been used as a substitute for calcium binding to tobacco mosaic virus (TMV). The high atomic number of lead has allowed us to use difference maps from X-ray fiber diffraction data to characterize a calcium-binding site in the virus. The metal ligands are slightly different from those previously believed to bind calcium to TMV, although the binding site is very close to one previously described. Two acetate groups are also bound to the lead atom. There is no significant backbone conformational change in the protein as a result of metal binding; the binding is accomplished by means of relatively small movements in amino acid side chains.

Binding Sites↗