Tectivirus
| Tectiviridae | |
|---|---|
| File:1gw7.jpg | |
| CryoEM model of Enterobacteria phage PRD1 capsid. PDB entry 1gw7[1] | |
| Virus classification | |
| Group: |
Group I (dsDNA)
|
| Family: | |
| Type Species | |
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Tectivirus is a genus of viruses, and is currently the only genus in the family Tectiviridae. Gram-negative bacteria serve as natural hosts. There are currently four species in this genus including the type species Enterobacteria phage PRD1.[2][3] Tectiviruses have no head-tail structure, but are capable of producing tail-like tubes of ~ 60×10 nm upon adsorption or after chloroform treatment.[citation needed] The name is derived from Latin tectus (meaning 'covered').
Virology
The virions of Tectiviridae species are non-enveloped, icosahedral and display a pseudo T=25 symmetry.[2] 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.
The genome is a single molecule of linear double-stranded DNA of 15 kilobases in length, and has 30 open reading frames.[2] 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.
| Genus | Structure | Symmetry | Capsid | Genomic Arrangement | Genomic Segmentation |
|---|---|---|---|---|---|
| Tectivirus | Icosahedral | T=25 | Non-Enveloped | Linear | Monopartite |
Life cycle
Viral replication is cytoplasmic. Entry into the host cell is achieved by adsorption into the host cell.[2] 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.[2] 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]
| Genus | Host Details | Tissue Tropism | Entry Details | Release Details | Replication Site | Assembly Site | Transmission |
|---|---|---|---|---|---|---|---|
| Tectivirus | Gram-negative bacteria | None | Injection | Lysis | Cytoplasm | Cytoplasm | Passive diffusion |
Taxonomy
Group: dsDNA
-
Family: Tectiviridae
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Genus: Tectivirus
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References
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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
