Tracking the green invaders: advances in imaging virus infection in plants

2010 ◽  
Vol 430 (1) ◽  
pp. 21-37 ◽  
Author(s):  
Jens Tilsner ◽  
Karl J. Oparka
Keyword(s):  
Virus Infection ◽  
Structural Biology ◽  
Plant Virus ◽  
Viral Proteins ◽  
Infection Process ◽  
Virus Infections ◽  
Advantages And Disadvantages ◽  
Technical Advances ◽  
Cellular Markers

Bioimaging contributes significantly to our understanding of plant virus infections. In the present review, we describe technical advances that enable imaging of the infection process at previously unobtainable levels. We highlight how such new advances in subcellular imaging are contributing to a detailed dissection of all stages of the viral infection process. Specifically, we focus on: (i) the increasingly detailed localizations of viral proteins enabled by a diversifying palette of cellular markers; (ii) approaches using fluorescence microscopy for the functional analysis of proteins in vivo; (iii) the imaging of viral RNAs; (iv) methods that bridge the gap between optical and electron microscopy; and (v) methods that are blurring the distinction between imaging and structural biology. We describe the advantages and disadvantages of such techniques and place them in the broader perspective of their utility in analysing plant virus infection.

scholarly journals Scanning and Actuation Techniques for Cantilever-Based Fiber Optic Endoscopic Scanners—A Review

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 251
Author(s):  
Mandeep Kaur ◽  
Pierre M. Lane ◽  
Carlo Menon
Keyword(s):  
Micro Electro Mechanical System ◽  
Modern Medicine ◽  
Image Resolution ◽  
Optical Fields ◽  
Scanning Method ◽  
Advantages And Disadvantages ◽  
Image Area ◽  
Technical Advances ◽  
Scanning Fiber

Endoscopes are used routinely in modern medicine for in-vivo imaging of luminal organs. Technical advances in the micro-electro-mechanical system (MEMS) and optical fields have enabled the further miniaturization of endoscopes, resulting in the ability to image previously inaccessible small-caliber luminal organs, enabling the early detection of lesions and other abnormalities in these tissues. The development of scanning fiber endoscopes supports the fabrication of small cantilever-based imaging devices without compromising the image resolution. The size of an endoscope is highly dependent on the actuation and scanning method used to illuminate the target image area. Different actuation methods used in the design of small-sized cantilever-based endoscopes are reviewed in this paper along with their working principles, advantages and disadvantages, generated scanning patterns, and applications.

Injured cells required for the initiation of plant virus infections

1969 ◽  
Vol 47 (3) ◽  
pp. 499-500 ◽  
Author(s):  
W. C. Kimmins ◽  
M. D. Casselman
Keyword(s):  
Phaseolus Vulgaris ◽  
Virus Infection ◽  
Plant Virus ◽  
Tobacco Necrosis Virus ◽  
Virus Infections ◽  
Necrosis Virus

To investigate whether a plant virus infection could be initiated in uninjured cells, the trifoliate leaves of Phaseolus vulgaris var. Prince were dipped into suspensions of tobacco necrosis virus. It is concluded that infection can only be established through injured leaf cells.

scholarly journals Proteolytic processing of plant proteins by potyvirus NIa proteases

2021 ◽  
Author(s):  
Huogen Xiao ◽  
Etienne Lord ◽  
Hélène Sanfaçon
Keyword(s):  
Virus Infection ◽  
Plant Virus ◽  
Plant Viruses ◽  
Proteolytic Processing ◽  
Plum Pox Virus ◽  
Plant Proteins ◽  
Host Proteins ◽  
Prediction Approach

The NIa protease of potyviruses is a chymotrypsin-like cysteine protease related to the picornavirus 3C protease. It is also a multifunctional protein known to play multiple roles during virus infection. Picornavirus 3C proteases cleave hundreds of host proteins to facilitate virus infection. However, whether or not potyvirus NIa proteases cleave plant proteins has so far not been tested. Regular expression search using the cleavage site consensus sequence [EQN]xVxH[QE]/[SGTA] for the plum pox virus (PPV) protease identified 90-94 putative cleavage events in the proteomes of Prunus persica (a crop severely affected by PPV), Arabidopsis thaliana and Nicotiana benthamiana (two experimental hosts). In vitro processing assays confirmed cleavage of six A. thaliana and five P. persica proteins by the PPV protease. These proteins were also cleaved in vitro by the protease of turnip mosaic virus (TuMV), which has a similar specificity. We confirmed in vivo cleavage of a transiently expressed tagged version of AtEML2, an EMSY-like protein belonging to a family of nuclear histone readers known to be involved in pathogen resistance. Cleavage of AtEML2 was efficient and was observed in plants that co-expressed the PPV or TuMV NIa proteases or in plants that were infected with TuMV. We also show partial in vivo cleavage of AtDUF707, a membrane protein annotated as lysine ketoglutarate reductase trans-splicing protein. Although cleavage of the corresponding endogenous plant proteins remains to be confirmed, the results show that a plant virus protease can cleave host proteins during virus infection and highlight a new layer of plant-virus interactions. Importance Viruses are highly adaptive and use multiple molecular mechanisms to highjack or modify the cellular resources to their advantage. They must also counteract or evade host defense responses. One well-characterized mechanism used by vertebrate viruses is the proteolytic cleavage of host proteins to inhibit the activities of these proteins and/or to produce cleaved protein fragments that are beneficial to the virus infection cycle. Even though almost half of the known plant viruses encode at least one protease, it was not known whether plant viruses employ this strategy. Using an in silico prediction approach and the well-characterized specificity of potyvirus NIa proteases, we were able to identify hundreds of putative cleavage sites in plant proteins, several of which were validated by downstream experiments. It can be anticipated that many other plant virus proteases also cleave host proteins and that the identification of these cleavage events will lead to novel antiviral strategies.

scholarly journals Double-Stranded RNA-Mediated Interference with Plant Virus Infection

2001 ◽  
Vol 75 (24) ◽  
pp. 12288-12297 ◽  
Author(s):  
F. Tenllado ◽  
J. R. Dı́az-Ruı́z
Keyword(s):  
Virus Infection ◽  
Plant Virus ◽  
Virus Infections ◽  
Transient Expression Assay ◽  
Double Stranded Rna ◽  
Posttranscriptional Gene Silencing ◽  
Specific Manner ◽  
Viral Sequences ◽  
Dose Dependent ◽  
Natural Virus

ABSTRACT Double-stranded RNA (dsRNA) has been shown to play a key role as an inducer of different interference phenomena occurring in both the plant and animal kingdoms. Here, we show that dsRNA derived from viral sequences can interfere with virus infection in a sequence-specific manner by directly delivering dsRNA to leaf cells either by mechanical inoculation or via an Agrobacterium-mediated transient-expression assay. We have successfully interfered with the infection of plants by three viruses belonging to the tobamovirus, potyvirus, and alfamovirus groups, demonstrating the reliability of the approach. We suggest that the effect mediated by dsRNA in plant virus infection resembles the analogous phenomenon of RNA interference observed in animals. The interference observed is sequence specific, is dose dependent, and is triggered by dsRNA but not single-stranded RNA. Our results support the view that a dsRNA intermediate in virus replication acts as efficient initiator of posttranscriptional gene silencing (PTGS) in natural virus infections, triggering the initiation step of PTGS that targets viral RNA for degradation.

scholarly journals Mechanisms of resistance to viruses

2002 ◽  
Vol 38 (SI 1 - 6th Conf EFPP 2002) ◽  
pp. S132-S135
Author(s):  
J.P.T. Valkonen
Keyword(s):  
Cell Death ◽  
Virus Infection ◽  
Virus Resistance ◽  
Rna Silencing ◽  
Subsequent Development ◽  
Viral Proteins ◽  
Virus Movement ◽  
Virus Infections ◽  
Viral Synergism ◽  
Multicellular Organisms

Resistance associated with a hypersensitive response (HR) and subsequent development of necrotic lesions (cell death) at the sites of virus infection can restrict virus movement in plants. Genes for HR are dominant and act on a gene-for-gene basis. Many viral proteins triggering HR have been identified. Also, several genes for HR-based virus resistance, or virus-induced cell death without resistance, have been isolated and characterized in plants, which provides novel insights to the mechanisms of virus resistance. Another international, major research frontier has formed more recently around RNA silencing, a universal RNA surveillance system and inducible virus defence mechanism in multicellular organisms. Many viral proteins interfere with different phases of RNA silencing. The data provide novel insights to break-down of resistance in mixed virus infections (viral synergism), resistance to virus movement, and recovery of plants from virus infection.

scholarly journals Recent Progress on Exosomes in RNA Virus Infection

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 256
Author(s):  
Liying Zhang ◽  
Yichen Ju ◽  
Si Chen ◽  
Linzhu Ren
Keyword(s):  
Rna Virus ◽  
Cell Types ◽  
Infection Process ◽  
Biologically Active ◽  
Pathological State ◽  
Virus Infections ◽  
Infected Cells ◽  
Host Genetic ◽  
Cell To Cell Transfer

Recent research indicates that most tissue and cell types can secrete and release membrane-enclosed small vesicles, known as exosomes, whose content reflects the physiological/pathological state of the cells from which they originate. These exosomes participate in the communication and cell-to-cell transfer of biologically active proteins, lipids, and nucleic acids. Studies of RNA viruses have demonstrated that exosomes release regulatory factors from infected cells and deliver other functional host genetic elements to neighboring cells, and these functions are involved in the infection process and modulate the cellular responses. This review provides an overview of the biogenesis, composition, and some of the most striking functions of exosome secretion and identifies physiological/pathological areas in need of further research. While initial indications suggest that exosome-mediated pathways operate in vivo, the exosome mechanisms involved in the related effects still need to be clarified. The current review focuses on the role of exosomes in RNA virus infections, with an emphasis on the potential contributions of exosomes to pathogenesis.

PERFUSION OF OVARIES IN VITRO AND IN VIVO

1972 ◽  
Vol 68 (2_Supplb) ◽  
pp. S285-S309 ◽  
Author(s):  
Kurt Ahrén ◽  
Per Olof Janson ◽  
Gunnar Selstam
Keyword(s):  
Perfusion System ◽  
Perfusion Technique ◽  
Preliminary Results ◽  
Advantages And Disadvantages

ABSTRACT This paper discusses in vivo and in vitro ovarian perfusion systems described so far in the literature. The interest is not focussed primarily on the results of these studies but rather on the advantages and disadvantages of the techniques and methods used. Another part of the paper summarizes the points which are most important, in our opinion, to take into consideration when developing an in vitro perfusion technique of the ovary. The last part of the paper gives a description of and some preliminary results from an in vitro perfusion system of the rabbit ovary which is under development in this laboratory.

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