Tobacco mosaic virus TMV

Extracts from 152 plant species, representing 46 different families, were screened for effects on tobacco mosaic virus (TMV) replication in cucumber cotyledons. Twenty species have shown enough activity to warrant further study. Several members of the Caprifoliaceae family increased virus replication. An extract of Lonicera involucrata enlarged the virus lesions in local lesion hosts and produced a thirty fold increase in virus titer, but had no effect on virus replication in systemic hosts. The active material appears to affect the virus defense mechanism of local lesion hosts. An extract of common geranium is an active virus inhibitor. It inactivates TMV and TMV-RNA (ribonucleic acid) in vitro by forming non-infectious complexes. In vivo, it also inhibited starch lesion formation in cucumber cotyledons incited by TMV infection. 

Cucumber cotyledons were inoculated with purified tobacco mosaic virus (TMV) 20 to 24 hours before vacuum infiltration with different concentrations of crude water extracts of plant leaves (4). After 7 days, inoculated leaves were harvested and stored 24 hours in the dark in a moist chamber to remove excess starch. Starch lesions were counted after clearing with alcohol and staining with an iodine-potassium iodide-lactic acid mixture. The inhibitory effects of various extracts were demonstrated by comparing lesion counts of treated cotyledons to counts on control cotyledons. 

Some virus particles have their protein subunits symmetrically packed in a helical array, forming hollow cylinders. The tobacco mosaic virus (TMV) is the classic example. X-ray diffraction data and electron micrographs have revealed that 16 subunits per turn of the helix project from a central axial hole that runs the length of the particle. The nucleic acid does not lie in this hole, but is embedded into ridges on the inside of each subunit and describes its own helix from one end of the particle to the other. 

A typical virus with helical symmetry is the tobacco mosaic virus (TMV). This is an RNA virus in which the 2130 identical protein subunits (each 158 amino acids in length) are arranged in a helix. In TMV, the helix has 16 1/2 subunits per turn and the overall dimensions of the virus particle are 18 X 300 nm. The lengths of helical viruses are determined by the length of the nucleic acid, but the width of the helical virus particle is determined by the size and packing of the protein subunits. 

Completely different mechanisms are involved in the self-assembly of the tobacco mosaic virus (TMV). This virus consists of single-strand RNA, which is surrounded by 2,130 identical protein units, each of which consists of 158 amino acid residues. A virus particle, which requires the tobacco plant as a host, has a rodlike structure with helical symmetry ( Stanley needles ). It is 300 nm long, with a diameter of 18nm. The protein and RNA fractions can be separated, and the viral... 

Fig. 2.1 Root growth (O) and accumulation of tobacco mosaic virus (TMV) ( ) in hairy roots of N. benthamiana. TMV concentrations were measured by ELISA. The error bars indicate standard errors from four replicate shake-flask cultures.

High molecular weight mesophases were first studied during the late 1930 s using suspensions of tobacco mosaic virus (TMV). Bawden and Pirie (26) reported a solution of TMV separated into two phases as the concentration was increased, one of which was birefringent. 

There are reports that plant virus inhibitors occur naturally in plants, and they could be proteins, glycoprote -ins, polysaccharides, phenols etc(7 5). Extracts of mosses, especially Sphagnum(76), algae(77) and Cassia of the family Leguminosae(7S) are effective in inhibiting tobacco mosaic virus(TMV), but much more work is needed to develop virici-des that may be sprayed safely and economically on crop plants in the field. 

True self-assembly is observed in the formation of many oligomeric proteins. Indeed, Friedman and Beychok reviewed efforts to define the subunit assembly and reconstitution pathways in multisubunit proteins, and all of the several dozen examples cited in their review represent true self-assembly. Polymeric species are also formed by true self-assembly, and the G-actin to F-actin transition is an excellent example. By contrast, there are strong indications that ribosomal RNA species play a central role in specifying the pathway to and the structure of ribosome particles. And it is interesting to note that the assembly of the tobacco mosaic virus (TMV) appears to be a two-step hybrid mechanism the coat protein subunits first combine to form 34-subunit disks by true self-assembly from monomeric and trimeric com-... 

Perez-Filgueira, D.M., Zamorano, PL, Dominguez, M.G., Taboga, O., Del Medico Zajac, M.P., Puntel, M., Romera, S.A., Morris, T.J., Borca, M.V., Sadir, A.M. (2003). Bovine herpes virus gD protein produced in plants nsing a recombinant tobacco mosaic virus (TMV) vector possesses authentic antigenicity. Vaccine 21 4201 209. 

More than half a century ago, Bawden and Pirie [77] found that aqueous solutions of tobacco mosaic virus (TMV), a charged rodlike virus, formed a liquid crystal phase at as very low a concentration as 2%. To explain such remarkable liquid crystallinity was one of the central themes in the famous 1949 paper of Onsager [2], However, systematic experimental studies on the phase behavior in stiff polyelectrolyte solutions have begun only recently. At present, phase equilibrium data on aqueous solutions qualified for quantitative discussion are available for four stiff polyelectrolytes, TMV, DNA, xanthan (a double helical polysaccharide), and fd-virus. 

Fig. lla-c. Phase boundary mass concentrations for aqueous solutions of three stiff polyions a xanthan (a double-helical polysaccharide) [78] b fd-virus [24] c tobacco mosaic virus (TMV) [23], Circles, experimental results curves, predictions by the first-order perturbation theory (see text)... 

Dilute polyelectrolyte solutions, such as solutions of tobacco mosaic virus (TMV) in water and other solvents, are known to exhibit interesting dynamic properties, such as a plateau in viscosity against concentration curve at very low concentration [196]. It also shows a shear thinning at a shear strain rate which is inverse of the relaxation time obtained from the Cole-Cole plot of frequency dependence of the shear modulus, G(co). 

Recently we were able to expand this approach to the fabrication of patterned arrays of bionanoparticles [85], The tobacco mosaic virus (TMV) is particularly... 

Wargacki SP, Pate B, Vaia RA (2008) Fabrication of 2D ordered films of tobacco mosaic virus (TMV) processing morphology correlations for convective assembly. Langmuir 24 5439-5444... 

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