Haloarcula hispanica SH1 virus

Haloarcula hispanica virus SH1
Virus classification
(unranked):	Virus
Realm:	Varidnaviria
Kingdom:	Helvetiavirae
Phylum:	Dividoviricota
Class:	Laserviricetes
Order:	Halopanivirales
Family:	Sphaerolipoviridae
Genus:	Alphasphaerolipovirus
Species:	Haloarcula hispanica virus SH1

Haloarcula hispanica SH1 virus is a double-stranded DNA virus that infects the archaeon Haloarcula hispanica.^[1] This virus has a number of unique features that were unlike any other known virus when it was described. However similarities have since been found with the Thermus thermophilus virus P23-77 and the Thermus aquaticus virus IN93. These viruses may form a new taxon when in the next revision of the taxonomy by the ICTV.

Virology

The virons are icosahedral in shape with a triangulation number of 28. The capsomers are decorated with a tower like structures and contain an inner lipid membrane lies beneath the protein capsid. The lipid membrane contains phosphatidylglycerol, phosphatidylglycerophosphate methyl ester and phosphatidylglycerosulfate. The base of the capsomer appears to be formed by a hexameric single beta barrel protein.^{[citation needed]}

There are 15 structural proteins in the capsid varying in molecular weight between 185 kilodaltons (kDa) and 4 kDa. These have been numbered from VP1 to VP 15. Seven appear to be minor components (VP5, VP6, VP8, VP11, VP13, VP14 and VP15).^{[citation needed]}

VP12 (molecular weight 9.8 kDa) has two membrane spanning helices suggesting it is an integral membrane protein.^{[citation needed]}

VP2 may be an elongated fiber like protein suitable for forming a spike.^{[citation needed]}

Genome

The genome is linear 30,898 base pairs in length and contains 309 base pair inverted terminal repeat sequences. The G+C content is 68.4%. It encodes 56 open reading frames (ORFs).^{[citation needed]}

The structural proteins correspond to the ORFs as follows:^{[citation needed]}

ORF13 – VP1
ORF23 – VP12
ORF24 – VP7
ORF25 – VP4
ORF27 – VP13
ORF28 – VP2
ORF29 – VP5
ORF30 – VP10
ORF31 – VP9
ORF32 – VP3
ORF33 – VP6

All the structural proteins are located in the middle of the genome.

ORF 17 encodes a protein with ATPase domain.

References

^ Bamford DH, Ravantti JJ, Rönnholm G, Laurinavicius S, Kukkaro P, Dyall-Smith M, Somerharju P, Kalkkinen N, Bamford JK (2005) Constituents of SH1, a novel lipid-containing virus infecting the halophilic euryarchaeon Haloarcula hispanica. J Virol 79(14):9097–9107

[Bamford2005-1] Bamford DH, Ravantti JJ, Rönnholm G, Laurinavicius S, Kukkaro P, Dyall-Smith M, Somerharju P, Kalkkinen N, Bamford JK (2005) Constituents of SH1, a novel lipid-containing virus infecting the halophilic euryarchaeon Haloarcula hispanica. J Virol 79(14):9097–9107

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