scholarly journals EVOLUTION OF PLANT VIRUSES: ADAPTATION TO HOSTS AND VECTORS

2008 ◽  
Vol 6 (2) ◽  
pp. 13-16 ◽  
Author(s):  
Jari Valkonen
Keyword(s):  
Cell Movement ◽  
Plant Viruses ◽  
Host Cells ◽  
Infection Cycle ◽  
Long Distance ◽  
New Host ◽  
Host Interactions ◽  
Plant Virus Evolution ◽  
Long Distance Movement ◽  
Virus Genomes

Viruses are obligate molecular pathogens. They depend on living host cells for their multiplication, including synthesis of the viral nucleic acids and proteins. The infection cycle of viruses in plants includes three main phases: i) replication, ii) cell to cell movement via plasmodesmata, and iii) long distance movement to different parts of the plant. During all these steps of the infection cycle viruses are challenged by the genetic variability of their hosts, which requires the virus to be adjusted to minor or major differences in virus-host interactions. These adjustments require mutations in the viral genome. Most plant viruses are also dependent on vector organisms for their spread to new host plants. The changes in virus genomes for better adaptability to the host should not compromise vector-transmissibility of progeny viruses. Host adaptation and vector adaptation can therefore be seen as the main forces influencing plant virus evolution.

scholarly journals The Rate of Cell-to-Cell Movement in Squash of Cucumber Mosaic Virus Is Affected by Sequences of the Capsid Protein

1999 ◽  
Vol 12 (7) ◽  
pp. 628-632 ◽  
Author(s):  
Sek-Man Wong ◽  
Sharon Swee-Chin Thio ◽  
Michael H. Shintaku ◽  
Peter Palukaitis
Keyword(s):  
Amino Acids ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Capsid Protein ◽  
Cell Movement ◽  
Systemic Infection ◽  
Long Distance ◽  
Local Movement ◽  
Long Distance Movement

The M strain of cucumber mosaic virus (CMV) does not infect squash plants systemically and moves very slowly in inoculated cotyledons. Systemic infection and an increase in the rate of local movement were observed when amino acids 129 or 214 of the M-CMV capsid protein (CP) were altered to those present in the Fny strain of CMV. While the opposite alterations to the CP of Fny-CMV inhibited systemic infection of squash, they did not show the same effects on the rates of both cell-to-cell and long-distance movement. However, the ability of CMV to infect squash systemically was affected by the rate of cell-to-cell movement.

scholarly journals Reciprocal function of movement proteins and complementation of long-distance movement of Cymbidium mosaic virus RNA by Odontoglossum ringspot virus coat protein

2005 ◽  
Vol 86 (5) ◽  
pp. 1543-1553 ◽  
Author(s):  
Prabha Ajjikuttira ◽  
Chiang-Shiong Loh ◽  
Sek-Man Wong
Keyword(s):  
Coat Protein ◽  
Transgenic Plants ◽  
Mosaic Virus ◽  
Cell Movement ◽  
Ringspot Virus ◽  
Deficient Mutant ◽  
Long Distance ◽  
Cymbidium Mosaic Virus ◽  
Odontoglossum Ringspot Virus ◽  
Long Distance Movement

Complementation of movement and coat proteins of the orchid-infecting potexvirus Cymbidium mosaic virus (CymMV) and tobamovirus Odontoglossum ringspot virus (ORSV) was investigated. Nicotiana benthamiana, which is susceptible to both CymMV and ORSV, was used as a model system. Four transgenic lines, each harbouring one of the movement protein (MP) or coat protein (CP) genes of CymMV or ORSV, were constructed. The MP of CymMV consists of three overlapping open reading frames, together called the triple-gene block (TGB). CymMV and ORSV mutants, each carrying an inactivated MP or CP, were generated from the respective biologically active full-length cDNA clones. Complementation was studied by infecting transgenic plants with in vitro transcripts generated from these mutants. The cell-to-cell movement of a movement-deficient CymMV was restored in transgenic plants carrying the ORSV MP transgene. Similarly, CymMV TGB1 transgenic plants were able to rescue the cell-to-cell movement of a movement-deficient ORSV mutant. ORSV CP transgenic plants supported systemic movement of a CymMV CP-deficient mutant. However, in these plants, neither encapsidation of CymMV RNA with ORSV CP nor CymMV CP expression was detected. Long-distance movement of an ORSV CP-deficient mutant was not supported by CymMV CP. The complementation of MPs and CPs of CymMV and ORSV facilitates movement of these viruses in plants, except for long-distance movement of ORSV RNA by CymMV CP.

Cell motility and cell morphology: How some viruses take control

1999 ◽  
Vol 1 (10) ◽  
pp. 1-16
Author(s):  
Geoffrey L. Smith ◽  
Christopher M. Sanderson
Keyword(s):  
Cell Motility ◽  
Cell Function ◽  
Control Cell ◽  
Host Cells ◽  
Productive Infection ◽  
Molecular Virology ◽  
Host Interactions ◽  
Cytopathic Effects ◽  
Cellular Genes ◽  
Virus Genomes

Viruses replicate inside host cells, where they use host biochemical and structural components to facilitate the production of new virus particles. As a consequence of co-evolution with their hosts, viruses have acquired host genes and genetic mutations that confer dominance over normal cell function. Research on virus–cell interactions has focused on the identification of mechanisms of virus dominance in order to develop therapeutic strategies for preventing productive infection. Although such research remains an essential part of molecular virology, viruses are also important genetic tools that can be used to analyse cell function. Because virus genomes contain genetic information, some of which was derived from host cells, it is possible that the analyses of virus–host interactions might lead to the identification of functionally dominant virus genes and novel eukaryotic counterparts. In this article, we have described how transforming and non-transforming viruses can control cell motility (cell migration or membrane projection), and explained how the analysis of virus cytopathic effects (CPEs) led to the identification of a novel family of cellular genes that regulate diverse aspects of cell motility.

scholarly journals Defective Movement of Viruses in the Family Bromoviridae Is Differentially Complemented in Nicotiana benthamiana Expressing Tobamovirus or Dianthovirus Movement Proteins

1998 ◽  
Vol 88 (7) ◽  
pp. 666-672 ◽  
Author(s):  
A. L. N. Rao ◽  
Bret Cooper ◽  
Carl M. Deom
Keyword(s):  
Nicotiana Benthamiana ◽  
Cell Movement ◽  
Red Clover ◽  
Amino Acid Identity ◽  
Progeny Virus ◽  
Long Distance ◽  
Movement Proteins ◽  
Brome Mosaic Bromovirus ◽  
Chlorotic Mottle ◽  
Long Distance Movement

Taxonomically distinct tobacco mosaic tobamovirus (TMV), red clover necrotic mosaic dianthovirus (RCNMV), cucumber mosaic cucumovirus (CMV), brome mosaic bromovirus (BMV), and cowpea chlorotic mottle bromovirus (CCMV) exhibit differences in their host range. Each of these viruses encodes a functionally similar nonstructural movement protein (MP) that is essential for cell-to-cell movement of a progeny virus. Despite the lack of significant amino acid identity among the MPs of CMV, TMV, and RCNMV, movement-defective CMV (CMVFnyΔMP-ΔKPN) was able to move locally and systemically in transgenic Nicotiana benthamiana expressing either TMV MP (NB-TMV-MP(+)) or RCNMV MP (NB-RCNMV-MP(+)). These observations contrast with those of previous studies in which transgenic N. tabacum cv. Xanthi plants expressing TMV MP supported only the cell-to-cell movement of CMVFnyΔMP-ΔKPN. To verify whether similar complementation could be observed for movement-defective bromoviruses, NB-TMV-MP(+) and NB-RCNMV-MP(+) plants were inoculated independently with movement-defective variants of BMV (B3ΔMP) and CCMV (CC3ΔMP). Neither NB-TMV-MP(+) nor NB-RCNMV-MP(+) was able to rescue the defective cell-to-cell and long-distance movement of B3ΔMP. In contrast, NB-RCNMV-MP(+) complemented the cell-to-cell, but not the long-distance, movement of CC3ΔMP. Taken together, these studies suggest that virus movement is a complex process and that, in some cases, the host species plays a major role in determining the long-distance movement function of a virus.

scholarly journals Citrus Tristeza Virus: Survival at the Edge of the Movement Continuum

2008 ◽  
Vol 82 (13) ◽  
pp. 6546-6556 ◽  
Author(s):  
Svetlana Y. Folimonova ◽  
Alexey S. Folimonov ◽  
Satyanarayana Tatineni ◽  
William O. Dawson
Keyword(s):  
Citrus Tristeza Virus ◽  
Cell Movement ◽  
Systemic Infection ◽  
Sour Orange ◽  
Citrus Species ◽  
Long Distance ◽  
Susceptible Host ◽  
Long Distance Movement ◽  
Tristeza Virus ◽  
Citrus Tristeza

ABSTRACT Systemic invasion of plants by viruses is thought to involve two processes: cell-to-cell movement between adjacent cells and long-distance movement that allows the virus to rapidly move through sieve elements and unload at the growing parts of the plant. There is a continuum of proportions of these processes that determines the degrees of systemic infection of different plants by different viruses. We examined the systemic distribution of Citrus tristeza virus (CTV) in citrus species with a range of susceptibilities. By using a “pure” culture of CTV from a cDNA clone and green fluorescent protein-labeled virus we show that both cell-to-cell and long-distance movement are unusually limited, and the degree of limitation varies depending on the citrus host. In the more-susceptible hosts CTV infected only a small portion of phloem-associated cells, and moreover, the number of infection sites in less-susceptible citrus species was substantially decreased further, indicating that long-distance movement was reduced in those hosts. Analysis of infection foci in the two most differential citrus species, Citrus macrophylla and sour orange, revealed that in the more-susceptible host the infection foci were composed of a cluster of multiple cells, while in the less-susceptible host infection foci were usually single cells, suggesting that essentially no cell-to-cell movement occurred in the latter host. Thus, CTV in sour orange represents a pattern of systemic infection in which the virus appears to function with only the long-distance movement mechanism, yet is able to survive in nature.

scholarly journals Varied Movement Strategies Employed by Triple Gene Block–Encoding Viruses

2010 ◽  
Vol 23 (10) ◽  
pp. 1231-1247 ◽  
Author(s):  
Jeanmarie Verchot-Lubicz ◽  
Lesley Torrance ◽  
Andrey G. Solovyev ◽  
Sergey Yu Morozov ◽  
Andrew O. Jackson ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Rna Virus ◽  
Triple Gene Block ◽  
Cell Movement ◽  
Future Research ◽  
Subcellular Targeting ◽  
Long Distance ◽  
Movement Proteins ◽  
Gene Block ◽  
Long Distance Movement

Several RNA virus genera belonging to the Virgaviridae and Flexiviridae families encode proteins organized in a triple gene block (TGB) that facilitate cell-to-cell and long-distance movement. The TGB proteins have been traditionally classified as hordei-like or potex-like based on phylogenetic comparisons and differences in movement mechanisms of the Hordeivirus and Potexvirus spp. However, accumulating data from other model viruses suggests that a revised framework is needed to accommodate the profound differences in protein interactions occurring during infection and ancillary capsid protein requirements for movement. The goal of this article is to highlight common features of the TGB proteins and salient differences in movement properties exhibited by individual viruses encoding these proteins. We discuss common and divergent aspects of the TGB transport machinery, describe putative nucleoprotein movement complexes, highlight recent data on TGB protein interactions and topological properties, and review membrane associations occurring during subcellular targeting and cell-to-cell movement. We conclude that the existing models cannot be used to explain all TGB viruses, and we propose provisional Potexvirus, Hordeivirus, and Pomovirus models. We also suggest areas that might profit from future research on viruses harboring this intriguing arrangement of movement proteins.

scholarly journals Acibenzolar-S-Methyl Restricts Infection of Nicotiana benthamiana by Plantago Asiatica Mosaic Virus at Two Distinct Stages

2019 ◽  
Vol 32 (11) ◽  
pp. 1475-1486 ◽  
Author(s):  
Yuki Matsuo ◽  
Fawzia Novianti ◽  
Miki Takehara ◽  
Toshiyuki Fukuhara ◽  
Tsutomu Arie ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Nicotiana Benthamiana ◽  
Fluorescent Protein ◽  
Potato Virus X ◽  
Defense Responses ◽  
Plant Viruses ◽  
Long Distance ◽  
Plantago Asiatica ◽  
Green Fluorescent ◽  
Long Distance Movement

Plant activators, including acibenzolar-S-methyl (ASM), are chemical compounds that stimulate plant defense responses to pathogens. ASM treatment inhibits infection by a variety of plant viruses, however, the mechanisms of this broad-spectrum and strong effect remain poorly understood. We employed green fluorescent protein (GFP)-expressing viruses and Nicotiana benthamiana plants to identify the infection stages that are restricted by ASM. ASM suppressed infection by three viral species, plantago asiatica mosaic virus (PlAMV), potato virus X (PVX), and turnip mosaic virus (TuMV), in inoculated cells. Furthermore, ASM delayed the long-distance movement of PlAMV and PVX, and the cell-to-cell (short range) movement of TuMV. The ASM-mediated delay of long-distance movement of PlAMV was not due to the suppression of viral accumulation in the inoculated leaves, indicating that ASM restricts PlAMV infection in at least two independent steps. We used Arabidopsis thaliana mutants to show that the ASM-mediated restriction of PlAMV infection requires the NPR1 gene but was independent of the dicer-like genes essential for RNA silencing. Furthermore, experiments using protoplasts showed that ASM treatment inhibited PlAMV replication without cell death. Our approach, using GFP-expressing viruses, will be useful for the analysis of mechanisms underlying plant activator–mediated virus restriction.

scholarly journals Interactions between Viral and Prokaryotic Pathogens in a Mixed Infection with Cardiovirus and Mycoplasma

2009 ◽  
Vol 83 (19) ◽  
pp. 9940-9951 ◽  
Author(s):  
Peter V. Lidsky ◽  
Lyudmila I. Romanova ◽  
Marina S. Kolesnikova ◽  
Maryana V. Bardina ◽  
Elena V. Khitrina ◽  
...  
Keyword(s):  
Animal Cell ◽  
Present Report ◽  
Electrophoretic Analysis ◽  
Plant Viruses ◽  
Immunofluorescence Assay ◽  
Encephalomyocarditis Virus ◽  
Host Cells ◽  
Ecological Niches ◽  
Caspase Inhibitor ◽  
Host Interactions

ABSTRACT In the natural environment, animal and plant viruses often share ecological niches with microorganisms, but the interactions between these pathogens, although potentially having important implications, are poorly investigated. The present report demonstrates, in a model system, profound mutual effects of mycoplasma and cardioviruses in animal cell cultures. In contrast to mycoplasma-free cells, cultures contaminated with Mycoplasma hyorhinis responded to infection with encephalomyocarditis virus (EMCV), a picornavirus, but not with poliovirus (also a picornavirus), with a strong activation of a DNase(s), as evidenced by the TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) immunofluorescence assay and electrophoretic analysis of host DNA. This degradation was reminiscent of that observed upon apoptosis but was caspase independent, judging by the failure of the specific pan-caspase inhibitor Q-VD-OPh to prevent it. The electrophoretic mobility of the enzyme responsible for DNA degradation and dependence of its activity on ionic conditions strongly suggested that it was represented by a DNase(s) of mycoplasma origin. In cells not infected with EMCV, the relevant DNase was dormant. The possibility is discussed that activation of the mycoplasma DNase might be linked to a relatively early increase in permeability of plasma membrane of the infected cells caused by EMCV. This type of unanticipated virus-mycoplasma “cooperation” may exemplify the complexity of pathogen-host interactions under conditions when viruses and microorganisms are infecting the same host. In the course of the present study, it was also demonstrated that pan-caspase inhibitor zVAD(OMe).fmk strongly suppressed cardiovirus polyprotein processing, illustrating an additional pitfall in investigations of viral effects on the apoptotic system of host cells.

scholarly journals The C terminus of the movement protein of Brome mosaic virus controls the requirement for coat protein in cell-to-cell movement and plays a role in long-distance movement

2004 ◽  
Vol 85 (6) ◽  
pp. 1751-1761 ◽  
Author(s):  
Atsushi Takeda ◽  
Masanori Kaido ◽  
Tetsuro Okuno ◽  
Kazuyuki Mise
Keyword(s):  
Coat Protein ◽  
Mosaic Virus ◽  
Movement Protein ◽  
Cell Movement ◽  
Brome Mosaic Virus ◽  
Wild Type ◽  
Long Distance ◽  
C Terminus ◽  
Mouth Disease Virus ◽  
Long Distance Movement

The 3a movement protein (MP) plays a central role in the movement of Brome mosaic virus (BMV). To identify the functional regions in BMV MP, 24 alanine-scanning (AS) MP mutants of BMV were constructed. Infectivity of the AS mutants in the host plant Chenopodium quinoa showed that the central region of BMV MP is important for viral movement and both termini of BMV MP have effects on the development of systemic symptoms. A green-fluorescent-protein-expressing RNA3-based BMV vector containing a 2A sequence from Foot-and-mouth disease virus was also constructed. Using this vector, two AS mutants that showed more efficient cell-to-cell movement than wild-type BMV were identified. The MPs of these two AS mutants, which have mutations at their C termini, mediated cell-to-cell movement independently of coat protein (CP), unlike wild-type BMV MP. Furthermore, a BMV mutant with a truncation in the C-terminal 42 amino acids of MP was also able to move from cell to cell without CP, but did not move systemically, even in the presence of CP. These results and an encapsidation analysis suggest that the C terminus of BMV MP is involved in the requirement for CP in cell-to-cell movement and plays a role in long-distance movement. Furthermore, the ability to spread locally and form virions is not sufficient for the long-distance movement of BMV. The roles of MP and CP in BMV movement are discussed.

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