Template:Short description Template:Use dmy dates Template:Virusbox Cystoviruses are a family of double-stranded RNA viruses that infect bacteria. They constitute the family Cystoviridae. The name of the group cysto derives from Greek kystis which means bladder or sack. There are seven genera in this family.<ref name="ICTVReport">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=ViralZone>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=NCBI>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
DiscoveryEdit
Pseudomonas virus phi6 was the first virus in this family to be discovered and was initially characterized in 1973 by Anne Vidaver at the University of Nebraska. She found that when she cultured the bacterial strain Pseudomonas phaseolicola HB1OY with halo blight infected bean straw, cytopathic effects were detected in cultured lawns, indicating that there was a lytic microbe or bacteriophage present.<ref name="Vidaver_1973">Template:Cite journal</ref>
In 1999, phi7–14 were identified by the laboratory of Leonard Mindich at the Public Health Research Institute associated with New York University. They did this by culturing various leaves in Lysogeny Broth and then plating the broth on lawns of Pseudomonas syringae pv phaseolicola. They were able to identify viral plaques from this and then subsequently sequence their genomes.<ref name="Mindich_1999" />
MicrobiologyEdit
StructureEdit
Cystovirus particles are enveloped, with icosahedral and spherical geometries, and T=13, T=2 symmetry. The virion diameter is around 85 nm.<ref name="ICTVReport" /><ref name="ViralZone" />
GenomeEdit
Cystoviruses have a tripartite double-stranded RNA genome which is approximately 14 kbp in total length. The genome is linear and segmented, and labeled as large (L) 6.4 kbp, medium (M) 4 kbp, and small (S) 2.9 kb in length. The genome codes for twelve proteins.<ref name="ICTVReport" /><ref name="ViralZone" />
Life cycleEdit
Cystoviruses enter the bacteria by adsorption on its pilus and then membrane fusion. Viral replication is cytoplasmic. Replication follows the double-stranded RNA virus replication model. Double-stranded RNA virus transcription is the method of transcription. The progeny viruses are released from the cell by lysis.<ref name="ICTVReport" /><ref name="ViralZone" />
Most identified cystoviruses infect Pseudomonas species, but this is likely biased due to the method of screening and enrichment.<ref name="Silander_2005">Template:Cite journal</ref> There are many proposed members of this family. Pseudomonas viruses φ7, φ8, φ9, φ10, φ11, φ12, and φ13 have been identified and named,<ref name="Mindich_1999">Template:Cite journal</ref> but other cystovirus-like viruses have also been isolated.<ref name="Silander_2005" /> These seven putative relatives are classified as either close (φ7, φ9, φ10, φ11) or distant (φ8, φ12, φ13) relatives to φ6,<ref name="Mindich_1999" /> with the distant relatives thought to infect via the LPS rather than the pili.<ref name="Gottleib_2002">Template:Cite journal</ref>
However, cystoviruses do not only infect Pseudomonas. But also bacteria of the genera Streptomyces,<ref name="Siddhart">Template:Cite journal</ref> Microvirgula,<ref name=Cai>Template:Cite journal</ref> Acinetobacter,<ref name="crippen">Template:Cite journal</ref> Lactococcus, Pectobacterium,<ref name="ncbi">Cystoviridae. NCBI Taxonomy.</ref> and possibly other bacterial genera.
TaxonomyEdit
The family contains the following genera and species (-virus denotes genus):<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
- Alphacystovirus
- Betacystovirus
- Deltacystovirus
- Epsiloncystovirus
- Gammacystovirus
- Orthocystovirus
- Zetacystovirus
Other unassigned phages:
- Streptomyces virus phi0<ref name="Siddhart"/>
- Lactococcus virus phi7-4<ref name="ncbi"/>
- Pectobacterium virus MA14<ref name="ncbi"/>
- Acinetobacter virus CAP3<ref name="crippen"/>
- Acinetobacter virus CAP4<ref name="crippen"/>
- Acinetobacter virus CAP5<ref name="crippen"/>
- Acinetobacter virus CAP6<ref name="crippen"/>
- Acinetobacter virus CAP7<ref name="crippen"/>
ReferencesEdit
External linksEdit
Template:Baltimore classification Template:Taxonbar Template:Authority control