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Descriptions are generated automatically from the ICTVdB database including links. Some descriptions are only very basic and links may point to documents that are not yet published on the Web.

00.077. Tymoviridae

Cite this publication as: ICTVdB Management (2006). 00.077. Tymoviridae. In: ICTVdB - The Universal Virus Database, version 3. Büchen-Osmond, C. (Ed), Columbia University, New York, USA

Cite this site as: ICTVdB - The Universal Virus Database, version 4. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/

Table of Contents

Classification

This is a description of a plant virus at the family level.

ICTVdB Virus Code: 00.077. Virus accession number: 00077FAM.
NCBI Taxon Identifier NCBI Taxonomy ID: 249184.

Virion Properties

Morphology

Virions consist of a capsid. Virus capsid is not enveloped, round with icosahedral symmetry (T=3). The capsid is isometric and has a diameter of 25-28-33 nm. Capsids appear round, or hexagonal in outline. The capsomer arrangement is clearly visible, or is not obvious. The capsid consists of 32 capsomers; 12 of which are pentons; 20 are hexons.

Capsids all have the same appearance and are frequently penetrated by stain and most centers are dark. Incomplete particles are found. They are devoid of nucleic acid characterized by capsids with dark centers in negative stain preparations.






















Electron micrograph by R.G. Milne, Istituto di Virologia, CRN, Torino, Italy.
Additional electron micrographs of tymoviruses can be viewed at the Picture Gallery.

Electron microscopic preparation and references: Virus preparation contains few virions, or many virions.
























Additional 3D image of virus reconstruction can be found at Virus World, Molecular Virology, Madison.




















Capsid structures, detailed structural and computational analysis are found in the Protein Data Bank (PDB) using VIPERdB, the VIrus Particle ExploreR 1ddl.

Physicochemical and Physical Properties

Virions have a buoyant density in CsCl of 1.26-1.46 g cm-3. There are 2-3 sedimenting component(s) found in purified preparations. The sedimentation coefficient is 106-125 S20w, or 119-120 S20w; of the other(s) are 42-64 S20w, or 54-57 S20w. Isoelectric point pH is 3.3-9.46. A260/A280 ratio is 0.64-8.51, or 0.87-1.63. The thermal inactivation point (TIP) is at 55-90°C, or 60-70°C. The longevity in vitro (LIV) is 2-100 days, or 3-32 days. Although the titer is dependent on the host, the decimal exponent (DEX) of the dilution end point is usually around 2-9, or 5. The infectivity is not changed by treatment with ether; retained when deproteinized with proteases; retained when deproteinized with phenol or detergent.

Nucleic Acid

The Mr of the genome constitutes 23-39% of the virion by weight. The genome is monopartite. Only one particle size of linear, positive-sense, single-stranded RNA is recovered. Minor species of non-genomic nucleic acid are also found in virions, or not found in virions. The encapsidated nucleic acid is mainly of genomic origin, but virions may also contain subgenomic RNA, that is mRNA. The complete genome is 6000-7600 nucleotides long. Genome is sequenced, but only an estimate is available, complete sequence is 6000-7600 nucleotides long. The genome has a base ratio of 13.6-20.5 % guanine; 17-24.1 % adenine; 31.3-41 % cytosine, or 50 % cytosine; 22.15-29.4 % uracil. The 5'-end of the genome has a methylated nucleotide cap; cap sequence type is m7G5'ppp5. The 3'-terminus has a subgenomic promoter, a conserved region known as "tymobox", or no subgenomic promoter region. The 3'-terminus has a tRNA-like structure, or no tRNA-like structure. The genome has an intergenic poly (A) region at 3' terminal poly A tract.

GenBank records for nucleotide sequences; complete genome sequences.

Proteins

Proteins constitute about 61-77% of the particle weight.

The viral genome encodes structural proteins and non-structural proteins. Virions consist of 1 or 2 structural proteins located in the capsid.

Structural Proteins: Capsid protein has a molecular mass of 20000-28000 Da; is the coat protein.

Non-Structural Proteins: Virus-coded non-structural proteins have been identified by sequence analysis and 2 non-structural protein(s) are found.

Biological Properties

Natural Host

Domain
Viral hosts belong to the Domain Eucarya.

Domain Eucarya
Kingdom Plantae.

Kingdom Plantae
Phylum Magnoliophyta (Angiosperms, Class Magnoliopsida (Dicotyledonae) and Liliopsida (Monocotyledonae).

General Symptoms in Plants Virus affects the vascular system, or photosynthetic system. Symptoms are expressed in the leaf.

Severity and Occurrence of Disease

Host: Infection is apparent, or not apparent. Signs and symptoms persist, or vary cyclically over a few weeks.

Transmission and Vector Relationships

Virus is transmitted by a vector, or not transmitted by a vector. Virus is transmitted by mechanical inoculation, or not transmitted by mechanical inoculation.

Histopathology: Virions are found in the cytoplasm, or chloroplast, or cell vacuole.

Cytopathology: Inclusions are present in infected cells, or not present in infected cells. Inclusion bodies in the host cell are found in the cytoplasm, or nucleus. Cytoplasmic inclusions are crystals, or membranous bodies, or viroplasma, or multivesiculated bodies.

References

The following generic references are cited in the most recent ICTV Report.

PubMed References.

Taxonomic Proposals and Changes

A taxonomic proposal has been submitted to the ICTV by the Plant Virus Subcommittee at the meeting in Washington, DC, April 2001, to create a new taxon. The proposal has been approved at the meeting of the Executive Committee in Houston, March 2002, the taxon has been designated as Family.



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DELTA - DEscription Language for TAxonomy developed by Dr Mike Dallwitz, Toni Paine and Eric Zurcher, CSIRO Entomology, Canberra, Australia. ICTVdB - The Universal Virus Database, developed for the International Committee on Taxonomy of Viruses by Dr Cornelia Büchen-Osmond is written in DELTA. The virus descriptions in ICTVdB are coded by, or using data from experts in the field of virology or members ICTV. The character list is the underlying code. All virus descriptions are based on the character list and natural language translations are automatically generated and formatted for display on the Web from the descriptions in DELTA-format. The description has been generated automatically from DELTA files. DELTA - DEscription Language for TAxonomy developed by Dr Mike Dallwitz, Toni Paine and Eric Zurcher, CSIRO Entomology, Canberra, Australia.

ICTVdB - The Universal Virus Database, developed for the International Committee on Taxonomy of Viruses (ICTV) by Dr Cornelia Büchen-Osmond, is written in DELTA. The virus descriptions in ICTVdB are coded by ICTV members and experts, or by the ICTVdB Management using data provided by the experts, the literature or the latest ICTV Report. The character list is the underlying code. All virus descriptions are based on the character list and natural language translations from the encoded descriptions are automatically generated and formatted for display on the Web.

Developer of the DELTA software: M. J. Dallwitz, T. Paine and E. Zurcher

ICTVdB and DELTA related References

Comments to ICTVdB Management
Last updated on 25 April 2006 by Cornelia Büchen-Osmond
Copyright © 2002    International Committee on Taxonomy of Viruses.    All rights reserved.


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