Alphapleolipovirus HHPV1, also known as Haloarcula hispanica pleomorphic virus 1 (HHPV-1) is a virus of the family Pleolipoviridae. It is a double stranded DNA virus that infects the halophilic archaeon Haloarcula hispanica.[1] It has a number of unique features unlike any previously described virus.[2][3]
| Alphapleolipovirus HHPV1 | |
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| Alphapleolipovirus virion | |
Virus classification 
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| (unranked): | Virus |
| Realm: | Monodnaviria |
| Kingdom: | Trapavirae |
| Phylum: | Saleviricota |
| Class: | Huolimaviricetes |
| Order: | Haloruvirales |
| Family: | Pleolipoviridae |
| Genus: | Alphapleolipovirus |
| Species: | Alphapleolipovirus HHPV1
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| Synonyms | |
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Virology
editThe virions are enveloped and pleomorphic is shape. The envelope contains a variety of lipids including cardiolipins, phosphatidylglycerols, phosphatidylglycerophosphate methyl esters and phosphatidylglycerosulfates. There are two major proteins in the envelope — VP3 (12 kilodaltons in weight) and VP4 (60 kilodaltons in weight).[1]
The virions exit the host without lysis suggesting a budding mechanism.[1]
Genome
editThe genome is a single molecule of double stranded DNA, circular, 8082 base pairs in length with a G+C content of 55.8%. It has eight open reading frames (ORFs). VP3 and VP4 are encoded by ORF3 and ORF4 respectively.[citation needed]
ORF1 is probably a replication initiation protein. ORF3 encodes an integral membrane protein with a 50 amino acid signal sequence and two transmembrane regions. Before the C-terminal transmembrane domain is a coiled-coil region. ORF7 contains a NTPase domain but its function is not clear.[citation needed]
Taxonomy
editExamination of the proteins and genome organisation of this virus suggests that it related to the single stranded DNA virus Halorubrum pleomorphic virus 1, the plasmid pHK2 and a region within the archeon Haloferax volcanii. It seems likely that the plasmid pHK2 may be a virus that can form circular plasmids and that the region within Haloferax volcanii is a prophage.[citation needed]
The similarity between these double stranded DNA elements and the single stranded virus Halorubrum pleomorphic virus 1 is currently unique. If this relationship can be confirmed for other viruses it suggests that the currently used Baltimore system of classification may be in need of revision.[citation needed]
References
edit- ^ a b c Roine E, Kukkaro P, Paulin L, Laurinavicius S, Domanska A, Somerharju P, Bamford DH (2010) New, closely related haloarchaeal viral elements with different nucleic acid types. J Virol 84(7):3682–89
- ^ Pietilä MK, Atanasova NS, Manole V, Liljeroos L, Butcher SJ, Oksanen HM, Bamford DH (2012). "Virion Architecture Unifies Globally Distributed Pleolipoviruses Infecting Halophilic Archaea". Journal of Virology. 86 (9): 5067–79. doi:10.1128/JVI.06915-11. PMC 3347350. PMID 22357279.
- ^ Pietilä MK, Laurinavicius S, Sund J, Roine E, Bamford DH (2010). "The single-stranded DNA genome of novel archaeal virus Halorubrum pleomorphic virus 1 is enclosed in the envelope decorated with glycoprotein spikes". J Virol. 84 (2): 788–798. doi:10.1128/JVI.01347-09. PMC 2798366. PMID 19864380.