Tectivirus
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Tectiviridae is a family of viruses with 12 species in five genera. Bacteria serve as natural hosts.[1][2] Tectiviruses have no head-tail structure, but are capable of producing tail-like tubes of ~ 60×10 nm upon adsorption or after chloroform treatment. The name is derived from Latin tectus (meaning 'covered').[3]
Virology
The virions of Tectiviridae species are non-enveloped, icosahedral and display a pseudo T=25 symmetry.[1] The capsid has two layers. The outer layer is a protein structure of 240 capsid proteins trimers, and the inner one is a proteinaceous lipid membrane which envelopes the virus genome. Apical spikes extending about 20 nanometers (nm) protrude from the icosahedrons vertices.Script error: No such module "Unsubst".
The genome is a single molecule of linear double-stranded DNA of 15 kilobases in length, and has 30 open reading frames.[1] It forms a tightly packed coil and encodes several structural proteins. It encodes about 30 proteins that are transcribed in operons. At least 9 structural proteins are present in the viron. The genome is about 66 megadaltons in weight and constitutes 14–15% of the virion by weight. Lipids constitute a further 15% by weight. Carbohydrates are not present.Script error: No such module "Unsubst".
Life cycle
Viral replication is cytoplasmic. Entry into the host cell is achieved by adsorption into the host cell.[1] After adsorption to the host cell surface the virion extrudes a tail-tube structure through a vertex for genome delivery into the host. Replication follows the DNA strand displacement model. DNA-templated transcription is the method of transcription.[1] Capsid proteins polymerize around a lipoprotein vesicle translocated in the cytoplasm by virion assembly factors.
Mature virons are released by lysis, which, in the case of PRD1, is achieved with the aid of virus-encoded lysis machinery consisting of four proteins: P15 (endolysin),[4] P35 (holin),[5] P36 and P37 (homologues of the Rz/Rz1 proteins of phage lambda).[6]
Taxonomy
Tectiviridae contains the following genera and species:[2]
Other unassigned phages:[7]
References
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- ↑ Unclassified Tectiviridae. NCBI Taxonomy.
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Further reading
- ICTVdB—The Universal Virus Database ICTVdB Management (2006). 00.068. Tectiviridae. In: ICTVdB—The Universal Virus Database, version 3. Büchen-Osmond, C. (Ed), Columbia University, New York, USA
- Virus Taxonomy: Eighth Report of the International Committee on Taxonomy of Viruses H.V. Van Regenmortel, D.H.L. Bishop, M. H. Van Regenmortel, Claude M. Fauquet (Eds)
- 68.0.1. Tectivirus Template:Webarchive