View source for Biology:Halspiviridae

{{Short description|Family of viruses}}
{{Italic title}}
{{Virusbox
| image             = Salterprovirus virion.jpg
| image_caption     = Diagram of virion structure
| image2            = File:His1 v1.jpg
| image2_caption    = [[Engineering:Transmission electron microscopy|Transmission electron micrograph]] of virions, negatively stained with [[Chemistry:Uranyl acetate|uranyl acetate]]. Scale bar = 100 nm.
| taxon = Salterprovirus
| range_map         = {{Location map|Victoria|lat_deg=-38.07|lon_deg=144.42|caption=}}
| range_map_caption = Locality of isolation: saltern crystalliser in Avalon, Victoria, Australia
| subdivision = 
* Salterprovirus His1
| synonyms          =
Salterprovirus
* ''Epsilonfusellovirus''
Salterprovirus His1
* ''His 1 virus'' <small>ICTV 2004</small>
}}

'''''Halspiviridae''''' is a family of viruses that consists of a single genus, '''''Salterprovirus''''', which consists of a single recognised species; '''''Salterprovirus His1''''' (hereafter, 'His1'). This virus was isolated from hypersaline water in Australia and was able to be cultured on the halophilic [[Biology:Archaea|archaeon]] ''Haloarcula hispanica''. Like many other archaeoviruses, His1 has an approximately limoniform (lemon-shaped) virion.<ref name="pmid9765495">{{cite journal | vauthors = Bath C, Dyall-Smith ML | title = His1, an archaeal virus of the Fuselloviridae family that infects Haloarcula hispanica | journal = Journal of Virology | volume = 72 | issue = 11 | pages = 9392–5 | date = November 1998 | pmid = 9765495 | pmc = 110367 | doi = 10.1128/JVI.72.11.9392-9395.1998 }}</ref><ref name="Bath_2006">{{cite journal | vauthors = Bath C, Cukalac T, Porter K, Dyall-Smith ML | title = His1 and His2 are distantly related, spindle-shaped haloviruses belonging to the novel virus group, Salterprovirus | journal = Virology | volume = 350 | issue = 1 | pages = 228–39 | date = June 2006 | pmid = 16530800 | doi = 10.1016/j.virol.2006.02.005 | doi-access =  }}</ref><ref name=ViralZone>{{cite web|title=Viral Zone|url=http://viralzone.expasy.org/all_by_species/190.html|publisher=ExPASy|access-date=15 June 2015}}</ref><ref name=ICTV>{{cite web|last1=ICTV|title=Virus Taxonomy: 2014 Release|url=http://ictvonline.org/virusTaxonomy.asp|access-date=15 June 2015}}</ref>

== Etymology ==
The family name, ''Halspiviridae'', is derived from <u>hal</u>ophilic and <u>spi</u>ndle-shaped, in reference to the habitat and virion morphology, respectively. The genus name, ''Salterprovirus'', is derived from <u>salty</u> <u>ter</u>minal <u>pro</u>tein <u>virus</u>, as the linear dsDNA genome has proteins attached to the [[Biology:Directionality (molecular biology)#5′-end|5′ termini]].<ref name="pmid9765495"></ref>

== Taxonomy ==
The virion has a spindle-shaped morphology and is similar in shape to that of viruses infecting thermophilic archaea, the ''[[Biology:Fuselloviridae|Fuselloviridae]]'', and His1 was originally described as a probable member of that group.<ref name="pmid9765495"></ref> However, it was later found that there is no genetic relationship and their replication strategies are entirely different, and so His1 was classified into a new group, genus ''Salterprovirus'' within the family ''Halspiviridae''.<ref>{{cite journal | vauthors = Adriaenssens EM, Sullivan MB, Knezevic P, van Zyl LJ, Sarkar BL, Dutilh BE, Alfenas-Zerbini P, Łobocka M, Tong Y, Brister JR, Moreno Switt AI, Klumpp J, Aziz RK, Barylski J, Uchiyama J, Edwards RA, Kropinski AM, Petty NK, Clokie MR, Kushkina AI, Morozova VV, Duffy S, Gillis A, Rumnieks J, Kurtböke İ, Chanishvili N, Goodridge L, Wittmann J, Lavigne R, Jang HB, Prangishvili D, Enault F, Turner D, Poranen MM, Oksanen HM, Krupovic M | display-authors = 6 | title = Taxonomy of prokaryotic viruses: 2018-2019 update from the ICTV Bacterial and Archaeal Viruses Subcommittee | journal = Archives of Virology | volume = 165 | issue = 5 | pages = 1253–1260 | date = May 2020 | pmid = 32162068 | doi = 10.1007/s00705-020-04577-8 | doi-access = free | hdl = 2381/43909 | hdl-access = free }}</ref> ''Halspiviridae'' has not been classified within any higher-ranked taxa.{{cn|date=November 2022}}

Environmental DNA sequences derived from Namib salt pans indicate the presence of currently unrecognised, distant relatives of His1.<ref>{{cite journal | vauthors = Adriaenssens EM, van Zyl LJ, Cowan DA, Trindade MI | title = Metaviromics of Namib Desert Salt Pans: A Novel Lineage of Haloarchaeal Salterproviruses and a Rich Source of ssDNA Viruses | journal = Viruses | volume = 8 | issue = 1 | pages = 14 | date = January 2016 | pmid = 26761024 | pmc = 4728574 | doi = 10.3390/v8010014 | doi-access = free }}</ref>

Another species of virus, now named ''Gammapleolipovirus His2'' (hereafter 'His2'), was originally considered to be related to His1,<ref name="Bath_2006" /><ref name=ViralZone/> but later analysis of the His2 virion revealed that this species actually belongs to the family ''[[Biology:Pleolipoviridae|Pleolipoviridae]]''.<ref>{{cite journal | vauthors = Bamford DH, Pietilä MK, Roine E, Atanasova NS, Dienstbier A, Oksanen HM | title = ICTV Virus Taxonomy Profile: Pleolipoviridae | journal = The Journal of General Virology | volume = 98 | issue = 12 | pages = 2916–2917 | date = December 2017 | pmid = 29125455 | pmc = 5882103 | doi = 10.1099/jgv.0.000972 }}</ref>

== Structure ==
The virus is enveloped, with limoniform or spindle-shaped morphology. Genomes are linear, around 14.5kb in length. The genome has 35 open reading frames.<ref name=ViralZone /> A negatively stained electron microscope (EM) picture of His1 virions is shown on the right of this page. There is some variation in particle length (e.g. example seen left of centre), but most display the typical limoniform capsid with a short tail. High resolution micrographs and cryoEM reconstructions have been published by Hong et al. (2015),<ref>{{cite journal|vauthors=Hong C, Pietilä MK, Fu CJ, Schmid MF, Bamford DH, Chiu W|date=February 2015|title=Lemon-shaped halo archaeal virus His1 with uniform tail but variable capsid structure|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=112|issue=8|pages=2449–54|doi=10.1073/pnas.1425008112|pmc=4345568|pmid=25675521|bibcode=2015PNAS..112.2449H|doi-access=free}}</ref> who gave average dimensions of 92 x 40&nbsp;nm with a 12&nbsp;nm tail.

{| class="wikitable sortable" style="text-align:center"
|-
! Structure !! Capsid !! Genomic arrangement !! Genomic segmentation
|-
|Limoniform||Protein||Linear||Monopartite
|}

== Replication cycle ==
Viral replication is cytoplasmic. Entry into the host cell is achieved by virus attachment to the host cell. An adsorption rate constant for His1 of 1.9 x 10<sup>−12</sup> ml min<sup>−1</sup> has been experimentally determined by Pietilä et al. (2013).<ref>{{cite journal | vauthors = Pietilä MK, Atanasova NS, Oksanen HM, Bamford DH | title = Modified coat protein forms the flexible spindle-shaped virion of haloarchaeal virus His1 | journal = Environmental Microbiology | volume = 15 | issue = 6 | pages = 1674–86 | date = June 2013 | pmid = 23163639 | doi = 10.1111/1462-2920.12030 }}</ref> DNA-templated transcription is the method of transcription. ''Haloarcula hispanica'' may serve as a host. Transmission occurs via passive diffusion.<ref name=ViralZone />

{| class="wikitable sortable" style="text-align:center"
|-
! Host details !! Tissue tropism !! Entry details !! Release details !! Replication site !! Assembly site !! Transmission
|-
|Archea: ''Haloarcula hispanica''||None||Injection||Lytic||Cytoplasm||Cytoplasm||Passive diffusion
|}

== Genome ==
{{Infobox genome
| image   = <!-- Karyotype, for instance -->
| caption =
| taxId   = NC_007914
| size    = 14,464 [[Biology:Nucleotide|nucleotide]]s
| year    = 2020
}}

The linear, dsDNA genome of His1 consists of [https://www.ncbi.nlm.nih.gov/nuccore/NC_007914 14,464 base-pairs] (bp), has imperfect inverted terminal repeat sequences of 105 bp, and is annotated to carry 35 protein coding genes, including a gene specifying a protein-primed DNA polymerase (B-family). The ends of the genome have a protein attached.<ref name="Bath_2006"/> The protein sequence of the polymerase is 42% identical to the polymerase specified by the gammapleolipovirus His2, even though the two viruses belong to very different taxonomic groups.{{cn|date=November 2022}}

== References ==
{{Reflist|2}}

== External links ==
* [http://viralzone.expasy.org/all_by_species/190.html Viralzone: ''Salterprovirus'']
* [http://ictvonline.org/virusTaxonomy.asp International Committee on Taxonomy of Viruses (ICTV)]

{{Baltimore classification}}
{{Taxonbar|from=Q7406092}}

[[Category:Double-stranded DNA viruses]]
[[Category:Virus genera]]
[[Category:Virus families]]

{{Sourceattribution|Halspiviridae}}