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CryoEM model of Enterobacteria phage PRD1 capsid. PDB entry 1gw7[1]
Virus classification
Group: Group I (dsDNA)
Family: Tectiviridae
Genus: Tectivirus

Bacillus anthracis phage AP50
Bacillus thuringiensis phage Bam35
Bacillus thuringiensis phage GIL01
Bacillus thuringiensis phage GIL16c
Bacillus phage ϕNS11
Enterobacteria phage L17
Enterobacteria phage PR3
Enterobacteria phage PR4
Enterobacteria phage PR5
Enterobacteria phage PR722
Enterobacteria phage PRD1
Streptococcus suis phage SS2-HA/SS2-ZY
Thermus phage P37-14

The Tectiviridae is a family of double-stranded DNA viruses that infect bacteria and archea. Tectiviridae 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').

There is a single genus in this family—genus Tectivirus.

The type species is Enterobacteria phage PRD1.


The virions of Tectiviridae species are non-enveloped, icosahedral and display a pseudo T=25 symmetry. 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. 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.

Life cycle[edit]

After adsorbion to the host cell surface the virion extrudes a tail-tube structure through a vertex for genome delivery into the host.

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),[2] P35 (holin),[3] P36 and P37 (homologues of the Rz/Rz1 proteins of phage lambda).[4]


  1. ^ San Martín, C; Huiskonen, JT; Bamford, JK; Butcher, SJ; Fuller, SD; Bamford, DH; Burnett, RM (2002). "Minor proteins, mobile arms and membrane-capsid interactions in the bacteriophage PRD1 capsid". Nature structural biology 9 (10): 756–63. doi:10.1038/nsb837. PMID 12219080. 
  2. ^ Caldentey J, Hänninen AL, Bamford DH (1994). "Gene XV of bacteriophage PRD1 encodes a lytic enzyme with muramidase activity". Eur J Biochem 225 (1): 341–346. doi:10.1111/j.1432-1033.1994.00341.x. PMID 7925454. 
  3. ^ Rydman PS, Bamford DH (2003). "Identification and mutational analysis of bacteriophage PRD1 holin protein P35". J Bacteriol 185 (13): 3795–3803. doi:10.1128/JB.185.13.3795-3803.2003. PMC 161566. PMID 12813073. 
  4. ^ Krupovic M, Cvirkaite-Krupovic V, Bamford DH (2008). "Identification and functional analysis of the Rz/Rz1-like accessory lysis genes in the membrane-containing bacteriophage PRD1". Mol Microbiol 68 (2): 492–503. doi:10.1111/j.1365-2958.2008.06165.x. PMID 18366440. 

Further reading[edit]

  • 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)

External links[edit]