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PubMed2000

[Cloning and infectivity analysis of the cDNAs of tobacco mosaic virus (tomato strain) and its attenuated virus(N14) genomes].

An oligonucletide primer with SP6 transcription promoter and the other primer with a KpnI site at 5' terminuses were used to prepare the cDNAs of tobacco mosaic virus(TMV, Chinese isolate) and its attenuated virus(N14, nitrite-treated mutant, tomato strain) genomic RNAs by RT-PCR. The cDNAs were cut into two fragments by BamHI and first cloned separately then recombined into pUC18 by the restriction endonucleases of BamHI, SmaI, HincII, PstI, SphI. The sequences of 5' and 3' terminal nucleotides (< 50 bp) were consistent with the reported references. The infectious clones(pTMV-Cv/pN14) have been obtained and corroborated by in vitro transcription with SP6 RNA polymerase and tobacco infection. Necrotic local lesions were observed in Nicotiana samsun NN induced by the transcripts from both pTMV and pN14 within 3-5 days after inoculation, systemic symptoms showed in single-lesion infected Nicotiana tobacum cv, coincided with symptoms of tobaccoes infected by TMV and N14.

Cloning, Molecular↗
PubMedDate not supplied

Chemical degradation of tobacco mosaic virus followed by infectivity assay, reverse transcription-polymerase chain reaction and gel electrophoresis.

In order to determine the detection limit for chemically treated virions by gel electrophoresis, reverse transcription-polymerase chain reaction (RT-PCR) and infectivity assay, tobacco mosaic virus (TMV) exposed to various concentrations of chemicals was studied. When virions were exposed to 0.2 N HCl for 30 mins, partially degraded TMV particles were observed by gel electrophoresis. Under the same exposure, a major RT-PCR amplified DNA product corresponding to the target size of 806 bp, which decreased as a function of time, could be detected for up to 60 mins of exposure. When virions were treated with NaOH (0.02 N or higher normality) for 5 mins, partially degraded virions were detected by gel electrophoresis, exhibiting multiple band patterns. Exposure of the virions to 0.1 N NaOH for 5 mins revealed severely degraded viral RNA, but disappearance of the amplified RT-PCR products was apparent during 30-60 mins of exposure. Therefore, these data showed clearly the difference in the detection limit of gel electrophoresis and that of RT-PCR for the degraded viral RNA. In addition, the infectivity assay showed that the number of local lesions in Nicotiana rustica were significantly reduced by more than 95% when the virus was exposed to 0.2 N HCl for 15 mins or 0.1 N NaOH for 10 mins. From these results we conclude that loss of infectivity was not related to that of PCR product. Other chemical disinfectants such as phenol or formalin were also found to be effective to reduce the virus infectivity, but a corresponding degradation of viral RNA was detected by neither gel electrophoresis nor RT-PCR.

Electrophoresis, Agar Gel↗
PubMed1976

Uptake of labelled tobacco mosaic virus by tobacco protoplasts in the presence of metabolic inhibitors and at low temperature.

In the presence of inhibitors of protein synthesis and energy metabolism, tobacco protoplasts were shown to retain 14C-labelled tobacco mosaic virus (14C-TMV) with the same intensity as in control. At 2 degrees C, the protoplasts retained 14C-TMV at approximately the same rate as at 25 degrees C. In protoplasts inocculated at different temperatures, approximately equal amounts of infectious virus were produced, this being possibly indicative of a non-physiological nature of the first stages of virus penetration into the protoplast.

Adsorption↗
PubMed2000

Rapid Construction of Full-length cDNA Clones of Tobacco Mosaic Virus and the Infectivity Assay of Its in Vitro Transcript.

The full-length cDNA of tobacco mosaic virus faba bean isolate (TMV-B) was amplified with RT-PCR in which T7 promoter sequence was added in the 5' terminus of its upstream primer, so that full-length cDNA was put directly under the control of a T7 promoter. The cDNA was cloned into plasmid pT7Blue and linear DNA was got by digesting the recombinant with KpnI or KpnI and PstI. Using these linear DNA and full-length PCR product as templates, respectively, their in vitro transcripts were inoculated to Nicotiana tabacum and Chenopodium amaranticolor. All of the transcripts had infectivity and produced symptoms similar to that of wild TMV. It was found that transcripts of the full-length PCR product had higher infectious efficiency than those of linear DNA.

Journal Article↗
PubMed2002

The origin of modern plant virology.

Plant virology, born with Mayer's work, saw a first (embryonic) phase of development during two decades (1900-1920) with outstanding contributions from Dimitri Ivanovski, Martinus Beijerinck, Erwin Baur and Harry Allard. Between 1920 and 1930 a second phase saw the elaboration of surprising hypotheses concerning the enigmatic nature of viruses and experimental evidence of great stress was obtained. Revolutionary renewal began from the mid-1930s on the basis of a body of knowledge which was organically assembled into the first textbook of plant virology published by Kenneth Smith in 1933. In 1922, the geneticist Hermann Muller put forward the hypothesis that considered viruses as possible genes. The theory was resumed in an apparently independent way by Benjamin Duggar and Joanne Karrer Armstrong in 1923, who considered TMV a biocolloidal self-reproducing protein, like genes appeared to be. This hypothesis, even if neglected by virologists, anticipated by some decades the functional nature of viruses and represented the first conceptual response to virus enigma. Considerable experimental results were obtained by James Johnson, who showed that plants could be infected by different viruses and who introduced a first rational system of plant virus classification. Harold McKinney showed that TMV could mutate. Harold Storey, Kenneth Smith and Harry Severin demonstrated that several viruses could be transmitted by insects and supplied the first interpretation of the relationship between virus and insect. Mayme Dvorak and Helen Purdy obtained the first experimental evidence of the antigenic power of plant viruses. Virus purification, first tentatively accomplished with physical methods, was brilliantly performed by chemical means. Finally, Francis Holmes elaborated the first suitable test to estimate virus infectivity. The evolution of plant virology from an empirical discipline to a biological science took place thanks to the work of one group of American and English scientists who must be regarded as the fathers of modern plant virology.

History, 20th Century↗
PubMed2001

A systemic resistance inducing antiviral protein with N-glycosidase activity from Bougainvillea xbuttiana leaves.

An antiviral protein from Bougainvillea xbuttiana leaves induced systemic resistance in host plants N. glutinosa and Cyamopsis tetragonoloba against TMV and SRV, respectively which was reversed by actinomycin D, when applied immediately or shortly after antiviral protein treatment. When the inhibitor was applied to the host plant leaves post inoculation, it was effective if applied upto 4 h after virus infection. It also delayed the expression of symptoms in systemic hosts of TMV. The inhibitor showed characteristic N-glycosidase activity on 25S rRNA of tobacco ribosomes, suggesting that it could also be interfering with virus multiplication through ribosome-inactivation process.

Antiviral Agents↗
PubMedDate not supplied

[Determination of the effectiveness of RNA cross-linking with protein induced by UV-radiation in potato X-virus particles].

The UV-irradiation was found to induce formation of the RNA-protein cross-links and intraviral RNA chain breaks in the particles of flexuous potato virus X (PVX). Using the technique developed previously for the rod-like tobacco mosaic virus (TMV), the quantum yields of RNA-protein cross-links and intraviral RNA polynucleotide chain breaks formation in the PVX were determined and found to be more or less close to those found for the intraviral TMV RNA.

Plant Viruses↗
PubMedDate not supplied

[The course of virus infection of Lycopersicon esculentum plants at high concentrations of heavy metals].

Effect of certain compositions of heavy metals on the course of the system infection of TMV in plants of tomatoes Lycopersicon esculentum L. under field conditions was investigated. It is shown that the simultaneous influence of the virus infection and heavy metals in concentration of 10 MPC (maximum permissible concentration) resulted in the decrease of the content of total chlorophyll in the investigated plants by degradation of chlorophyll A; that was more considerable decrease as compared with separate influence of each of the factors. Treatment of plants by toxical concentrations of lead and zinc led to inconsiderable delay in development of the system TMV infection together with the increase of the virus content in plants 2 and more times, that evidences for the probable synergism in the action of the given heavy metals and virus infection. On the contrary, copper, though it decreased the content of total chlorophyll, manifested the protective properties and restricted essentially the virus accumulation in a plant as a whole.

Agriculture↗
PubMed2005

Poststenotic flow and intracranial hemodynamics in patients with carotid stenosis: transoral carotid ultrasonography study.

BACKGROUND AND PURPOSE: In severe carotid stenosis, blood supply via the poststenotic internal carotid artery (ICA) and collateral pathways determine cerebral perfusion. We investigated whether poststenotic flow on transoral carotid ultrasonography (TOCU) is predictive of cerebral hemodynamics. METHODS: Eighty-eight patients with unilateral carotid stenosis underwent TOCU to analyze blood flow velocity and poststenotic diameter of the extracranial ICA. Intracranial collaterals and cerebral hemodynamics were assessed with selective angiography and single photon emission CT. RESULTS: Poststenotic diameter (P <.0001) and velocities (peak systolic velocity [PSV], time-averaged mean velocity [TMV], end-diastolic velocity [EDV]; all P < or = .009) decreased with stenotic severity. Poststenotic diameter was correlated with PSV (r=0.36, P=.0005), EDV (r=0.32, P=.002), and TMV (r=0.39, P=.0001). Poststenotic flow was significantly lower with collateral pathways than without pathways (P < or = .02) and significantly decreased as the number of the collaterals increased (P <.0001). Flow <5 mL/s indicated collaterals (81% sensitivity, 80% specificity). When flow was <5 mL/s, the asymmetry index in the middle cerebral artery (MCA) territory was significantly low during rest (P=.003) and after acetazolamide challenge (P=.006). Poststenotic flow velocity was associated with baseline (P=.007) and postacetazolamide (P=.0009) MCA asymmetry indexes. CONCLUSION: Poststenotic ICA flow measured with TOCU reflects collateral flow and cerebral hemodynamics in patients with severe carotid stenosis. This technique may provide new parameters for screening patients with hemodynamically significant carotid stenosis.

Acetazolamide↗
PubMed2003

[Screening of proteins anti-tobacco mosaic virus in Pleurotus eryngii].

Proteins were obtained by ion-exchange chromatography and gel filtration from the dry sample of Pleurotus eryngii. In terms of detection on local lesion host, these components were confirmed to be anti-TMV and their inhibition rates reach more than 70%, or even 99%. The protein named xb68Ab of MW 23.7kD was purified by ion-exchange chromatography and gel filtration its inhibition rate against TMV are 99.43% and 98.9% on Nicotiana glutionosa and Chenopodium amaranticolor, respectively.

Antiviral Agents↗
PubMedDate not supplied

[Study of the conformational mobility of globular proteins by pulse methods of NMR].

The protein spin-echo decay and recovery of longitudinal magnetization were studied in seven globular proteins: cytochrome C, ribonuclease, lysozyme, DNA, hemoglobin, serum albumin and gamma-globulin in D2O solutions. For comparison the Tobacco mosaic virus (TMV) protons in D2O solutions were also investigated. The spin-echo decay of all 7 proteins can be separated into three components: a slowly decaying component with an amplitude of about 10% of the amplitude of the total signal, intermediately and fastly decaying components, the two latter being comparable in amplitudes. Longitudinal relaxation is more simple in character. The value of T2 of the protons responsible for the fastly decaying components in linearly dependent on the molecular weight of the protein, a fact indicating that the regions of the proteins with a "rigid" structure can be responsible for this component. The intermediate component, whose contribution increases with temperature, was ascribed to the mobile regions of the protein, and the slowly decaying component to the mobile protein side chains. Weak dependence of T1 on the protein molecular weight and some other obtained data give additional evidence for the presence of motion within macromolecules. The peculiarities of this motion is in good correspondence with the notion about the existence of the segmental motion of the polypeptide chain (conformational mobility of the protein). In contrast to proteins the spin-echo decay of TMV lacked the slow component and the "solid" echo signal was observed which indicates the existence of a "rigid" structure in the macromolecules of the virus.

Cytochrome c Group↗
PubMedDate not supplied

[Use of a cell-free protein synthesizing system from cells of ascites carcinoma Krebs-2 for RNA translation of plant viruses].

Cell-free translation in Krebs-2 extracts was optimized for RNAs of two plant viruses; potato virus X (PVX, potexvirus), and tobacco mosaic virus (TMV, tobamovirus). PVX and TMV RNAs programmed synthesis of similar sets of polypeptides in both the Krebs-2 extracts and the rabbit reticulocyte lysates, major virus-specific products being the same in molecular weight in both in vitro systems. PVX structural protein (p29) was absent among polypeptides synthesized in the Krebs-2 system but was readily identified by immuno-precipitation among the ones synthesized in the reticulocyte lysate system. The "cap" analog, m7Gpp, inhibited the synthesis of all the polypeptides programmed by PVX RNA in the Krebs-2 system. The synthesis of only a few of the most high molecular weight products in the reticulocyte lysate system was inhibited, the synthesis of a number of low molecular weight products (and among them p29) was even stimulated. Thus, the PVX capped messengers derived from PVX genomic RNA due to its fragmentation with endogenous nuclease activities. The use of the Krebs-2 system allows to avoid activation of internal PVX genes.

Animals↗
PubMedDate not supplied

[Mannan sulfates--inducers of plant resistance to viral infection].

Mannan sulphates (MS) synthesized on the basis of extracellular linear mannan (LM) of Rhodotorula rubra induce resistance of Immune-580 tobacco and thornapple (Datura stramonium) to tobacco mosaic virus (TMV). The resistance is manifested in a decrease in the number and/or size of viral local lesions (LL) in MS-treated (mg/ml) leaf halves. The reduction in the LL size does not seem to be due to the direct inhibition of TMV multiplication by the polysaccharide as the virus accumulation in the tissues of the systemic host (Samsun tobacco) does not decrease when MS is used 15 min after infection. The induced resistance is partially inhibited by actinomycin D and completely by heating (32 degrees C). Unlike MS, neutral LM decreases only the number of LL on the treated parts of the tissue but does not influence their size. The antiviral activity of LM does not change in the presence of actinomycin D. The possible mechanisms of the LM and MS protective effect in plants are discussed.

Dactinomycin↗
PubMedDate not supplied

[Molecular weight and several features of the structure of yeast polysaccharides possessing antiviral properties].

By the methods of biogel R-10, R-30, R-60 and R-200 gel filtration, sedimentation analysis and IR-spectroscopy polysaccharides isolated from yeast Candida tropicalis 3b, C. arborea KAM-1 and a commercial yeast extract (Merck) were investigated. The effect of the preparations on TMV was also studied. Polysaccharides consisted primarily of glucanes with a molecular weight of 10000-16500. The yeast extract preparation also included mannane with a molecular weight of 48000. IV-spectra of the purified preparations were in the main identical and were typical of polysaccharides. The mannane containing preparation inhibited TMV more significantly that glucane containing preparations. The interaction between physical parameters, structure and biological activity of the biopolymers tested is discussed.

Antiviral Agents↗
PubMedDate not supplied

[Comparative study of the antiviral properties of histones of animal and plant origin].

The antiviral properties of histones of animal (thymus) and plant (French beans) origin were studied in plants and with a plant virus, tobacco mosaic virus (TMV). Histones of the thymus and French beans were shown to be able to inhibit TMV reproduction. The antiviral properties of histones were found to depend on their concentration, pH, and to be determined by the modes of their introduction into leaves. The manifestation of the antiviral properties of histones seems to require not only their direct contact with virus but also a certain exposure on the leaf. The similarities of antiviral protective mechanisms of plants and animals determined by substances of the protein nature are discussed.

Animals↗
PubMed1979

Antiphytoviral activity of 2,4 dioxo hexahydro triazine.

Three treatments with 2,4 dioxo hexahydro triazine (DHT) significantly reduced the concentration of potato virus X (PVX) in systemically infected tobacco plants. In hypersensitive plants DHT caused a reduction in the number of local lesions produced by PVX. In systemic and hypersensitive hosts, treatment with DHT resulted in a more or less marked reduction in the concentration of, and in the number of local lesions caused by, potato virus Y (PVY), potato virus A (PVA), tobacco mosaic virus (TMV), and cucumber mosaic virus (CMV). Three days after treatment with DHT the incorporation of 32P into TMV RNA was significantly reduced, while that into host RNA was less affected.

Antiviral Agents↗
PubMed1984

Effect of lysolecithin analogues on plant viruses.

Newly synthesized lysolecithin analogues 2-0-hexadecyl-glycero-3-phosphocholine (1) and its methyl (2), ethyl (3) and benzyl (4) derivatives were tested with regard to the anti- phytoviral effect on potato virus X ( PVX ), red clover mottle virus ( RCMV ) and tobacco mosaic virus (TMV). The first two compounds (1, 2) reduced markedly the content of PVX and RCMV in systemically infected host plants as evidenced by precipitin test and bio-assay. Whereas compounds (1), (2) and (3) did not significantly influence the local lesion formation caused by TMV, compound (4) increased the number of necrotic lesions. In the presence of all four lysolecithin analogues, especially of (1), (2) and (3) the infectivity of virus particles was reduced.

Antiviral Agents↗
PubMed1983

Effect of abscissic acid on tobacco mosaic virus.

Abscisic acid (ABA) did not affect the infectivity of tobacco mosaic virus (TMV) in vitro. The same dilutions of ABA when applied on the leaves of Chenopodium amaranticolor Coste and Reyn. at different intervals before inoculation affected development of local lesions variably at different dilutions. The inhibition of local lesion formation was reduced at other intervals leading to stimulation at thirty minutes and six hours intervals. Post-inoculation treatments with 2 mg/l of ABA gave stimulation of local lesion formation, though other dilutions gave inhibition. Viral concentration was stimulated in the tomato seedlings root dipped in 0.2 mg/l of ABA for 6 hours and inoculated 24 hours after transplantation. Incorporation of different concentrations of ABA into tissue culture medium reduced the growth of the TMV infected tobacco callus tissue and stimulated the infectivity of the tissue grown over it assayed after three weeks.

Abscisic Acid↗