{{Short description|Family of viruses}} {{cs1 config|name-list-style=vanc}} {{Use dmy dates|date=April 2017}} {{Virusbox | image = 1gw7.jpg | image_caption = CryoEM model of Enterobacteria phage PRD1 capsid. PDB entry {{PDBe|1gw7}}<ref>{{cite journal|pmid=12219080|year=2002|last1=San Martín|first1=C|last2=Huiskonen|first2=JT|last3=Bamford|first3=JK|last4=Butcher|first4=SJ|last5=Fuller|first5=SD|last6=Bamford|first6=DH|last7=Burnett |first7=RM|title=Minor proteins, mobile arms and membrane-capsid interactions in the bacteriophage PRD1 capsid|volume=9|issue=10|pages=756–63|doi=10.1038/nsb837|journal=Nature Structural Biology|s2cid=32856328 }}</ref> | taxon = Tectiviridae | display_parents = 3 | subdivision_ranks = Genera | subdivision = See text }}

'''''Tectiviridae''''' is a family of viruses with 12 species in five genera. Bacteria serve as natural hosts.<ref name=ViralZone>{{cite web|title=Viral Zone|url=http://viralzone.expasy.org/all_by_species/579.html|publisher=ExPASy|access-date=15 June 2015}}</ref><ref name=ICTV>{{cite web|title=Virus Taxonomy: 2024 Release|url=https://ictv.global/taxonomy|publisher=International Committee on Taxonomy of Viruses|access-date=24 March 2025}}</ref> Tectiviruses have no head-tail structure, but are capable of producing tail-like tubes of ~ 60×10&nbsp;nm upon adsorption or after chloroform treatment. The name is derived from Latin ''tectus'' (meaning 'covered').<ref name=ictvreport >{{cite web|url=https://talk.ictvonline.org/ictv-reports/ictv_9th_report/dsdna-viruses-2011/w/dsdna_viruses/133/tectiviridae|archive-url=https://web.archive.org/web/20190424161051/https://talk.ictvonline.org/ictv-reports/ictv_9th_report/dsdna-viruses-2011/w/dsdna_viruses/133/tectiviridae|url-status=dead|archive-date=24 April 2019|title=ICTV Ninth Report; 2009 Taxonomy Release: ''Tectiviridae''|author=<!--Not stated-->|website=ICTV|access-date=18 September 2020}}</ref>

==Virology== thumb|Entry mechanism Enterobacteria phage PRD1 The virions of ''Tectiviridae'' species are non-enveloped, icosahedral and display a pseudo T=25 symmetry.<ref name=ViralZone /> 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&nbsp;nanometers (nm) protrude from the icosahedrons vertices.<ref name=ictvreport />

The genome is a single molecule of linear double-stranded DNA of 15 kilobases in length, and has 30 open reading frames.<ref name=ViralZone /> 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.<ref name=ictvreport />

==Life cycle== Viral replication is cytoplasmic. Entry into the host cell is achieved by adsorption into the host cell.<ref name=ViralZone /> 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.<ref name=ViralZone /> Capsid proteins polymerize around a lipoprotein vesicle translocated in the cytoplasm by virion assembly factors.<ref name=ViralZone />

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),<ref>{{cite journal|title=Gene XV of bacteriophage PRD1 encodes a lytic enzyme with muramidase activity|journal=Eur J Biochem|year=1994|volume=225|issue=1|pages=341–346|doi=10.1111/j.1432-1033.1994.00341.x|pmid=7925454|vauthors=Caldentey J, Hänninen AL, Bamford DH |doi-access=free}}</ref> P35 (holin),<ref>{{cite journal|title=Identification and mutational analysis of bacteriophage PRD1 holin protein P35|journal=J Bacteriol|year=2003|volume=185|issue=13|pages=3795–3803|doi=10.1128/JB.185.13.3795-3803.2003|pmid=12813073|vauthors=Rydman PS, Bamford DH |pmc=161566}}</ref> P36 and P37 (homologues of the Rz/Rz1 proteins of phage lambda).<ref>{{cite journal|title=Identification and functional analysis of the Rz/Rz1-like accessory lysis genes in the membrane-containing bacteriophage PRD1|journal=Mol Microbiol|year=2008|volume=68|issue=2|pages=492–503|doi=10.1111/j.1365-2958.2008.06165.x|pmid=18366440|vauthors=Krupovic M, Cvirkaite-Krupovic V, Bamford DH |doi-access=free}}</ref>

==Taxonomy== ''Tectiviridae'' contains the following genera and species:<ref name=ICTV /> * ''Alphatectivirus'' ** ''Alphatectivirus PR4'' ** ''Alphatectivirus PRD1'' * ''Betatectivirus'' ** ''Betatectivirus AP50'' ** ''Betatectivirus Bam35'' ** ''Betatectivirus GIL16'' ** ''Betatectivirus sato'' ** ''Betatectivirus sole'' ** ''Betatectivirus Wip1'' * ''Deltatectivirus'' ** ''Deltatectivirus forthebois'' ** ''Deltatectivirus wheeheim'' * ''Epsilontectivirus'' ** ''Epsilontectivirus toil'' * ''Gammatectivirus'' ** ''Gammatectivirus GC1''

Other unassigned phages:<ref>[https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=2047787&lvl=3&lin=f&keep=1&srchmode=1&unlock Unclassified Tectiviridae]. NCBI Taxonomy.</ref> * Thermus virus phiKo * Microbacterium virus Badulia * Microbacterium virus MuffinTheCat

==References== {{Reflist}}

==Further reading== * [https://web.archive.org/web/20041206110941/http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.068.htm 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 * [https://web.archive.org/web/20070224232458/http://www.microbiologybytes.com/virology/VirusGroups.html 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) * [http://www.ictvdb.rothamsted.ac.uk/ICTVdB/68010000.htm 68.0.1. Tectivirus] {{Webarchive|url=https://web.archive.org/web/20070928130124/http://www.ictvdb.rothamsted.ac.uk/ICTVdB/68010000.htm |date=28 September 2007 }}

==External links== * [http://viralzone.expasy.org/all_by_species/579.html '''Viralzone''': Tectivirus] * [http://ictvonline.org/virusTaxonomy.asp '''ICTV'''] {{Baltimore classification}} {{Taxonbar|from=Q569755}}

Category:Tectiviridae Category:Bacteriophages Category:Virus families