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00.053.0.01. Plasmavirus
Cite this publication as: ICTVdB Management (2006).
00.053.0.01. Plasmavirus. In: ICTVdB - The Universal Virus Database,
version 4. 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/
This is a description of a
mycoplasma virus at the genus level.
ICTVdB Virus Code: 00.053.0.01. Virus accession number:
053001GE. Obsolete virus code: 53.0.1.; superceded accession number: 53010000.
NCBI Taxon Identifier NCBI Taxonomy ID:
10473.
Name, Synonyms and Lineage
The taxon has the
accepted ICTV name.
Synonym(s): pleomorphic phages. Virus is of the family
00.053.
Plasmaviridae.
Virions consist of an envelope, a nucleoprotein complex,
and a core, or a capsid. Virus capsid is enveloped. Virions are spherical to
pleomorphic; spherical structures that lack cores are common (thin sections show
particles with lucent centers, and virions with densely stained centers,
seemingly containing condensed DNA). Virions measure
(50-)80(-125) nm in diameter with a loose fitting membrane
(baggy membrane). A regular capsid structure is not detectable. The core is
spherical (and densely stained in thin sections, consists of a nucleoprotein
complex. Structure not detectable, but images of thin sections are suggesting an
asymmetric nucleoprotein condensation bounded by a lipid-protein membrane. The
genome is condensed.
Virions are sensitive to treatment with or inactivated by
ether, non-ionic detergents (Brij-58, Triton-X, and Nonidet P-40), chloroform,
heat. The infectivity is not affected by irradiation (virions can be reactivated
after UV irradiation in host cells by excision and SOS DNA repair systems,
decreased when deproteinized with proteases.
The
genome is not segmented and contains a single molecule of circular,
supercoiled, double-stranded DNA. The complete genome is 12000
nucleotides long. The DNA (of Acholeplasma phage L2) is fully
sequenced, complete sequence is 11965 nucleotides long. The genome has
a guanine + cytosine content of 32 %.
GenBank records for
nucleotide sequences;
complete genome sequences.
The viral
genome encodes structural proteins. Virions consist of at least 4 structural
protein(s) located in the envelope.
Lipids are
present and located in the envelope. The composition of viral
lipids and host cell membranes are similar. The lipids are of host origin
and are derived from host cell membranes (and variation of host
cell fatty acid composition leads to virions with corresponding fatty acid
composition variations). Lipids in the viral membrane have a bilayer structure.
Carbohydrates have not been reported.
Genome Organization and Replication
Infection and Replication: Infection
involves a noncytocidal productive infectious cycle that is followed
by a lysogenic cycle in each infected cell. Prophage DNA must be activated
(derepressed) before replication. After initial replication of viral genome the
infecting nucleic acid may become latent within the host; complete. Lysogeny
involves integration into the host chromosome at a unique site. The
host chromosome; due to a repressor, lysogens are resistant to superinfection by
homologous virus. Lysogens are not resistant to superinfection by heterologous
virus (apparently due to a repressor). Latent infection can be induced by
UV-irradiation, or mitomycin C.
Transcription: The virus codes for at
least 15 ORF(s). The viral genome is transcribed from the viral sense
strand.
At least 11 viral mRNA(s) is/are transcribed with an overlap; viral
mRNA(s) is/are transcribed from at least 8 promoter(s, viral mRNA(s) is/are
transcribed in a unidirectional coding arrangement.
Release: Infected cells produce
prophages. Host cells survive as lysogens. Noncytocidal infection involves
progeny virus release. Virus is released from host cell by budding
through the cell membrane.
Natural Host
Domain
Viral hosts belong to the Domain
Bacteria.
Domain Bacteria
Phylum Firmicutes.
Host Classification Virus infects Division
Tenericutes; Class Mollicutes; Family Acholeplasmataceae; Genus
Acholeplasma; Species laidlawii.
Virus found in Acholeplasma laidlawii, and possibly A.
modicum and A. oculi strains.
Type species 00.053.0.01.001.
Acholeplasma phage L2 .
List of Species in the
Genus.
Tentative Species in the
Genus.
Data Sources and
Contributions
The description has been compiled from data in the
ICTV Report presented by Maniloff J.
The
following generic references are cited in the most recent ICTV Report.
PubMed References.
Taxon images: EM from Jack Maniloff, University of
Rochester, New York.