| Salterprovirus | |
|---|---|
 | |
| Diagram ofvirion structure | |
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| Transmission electron micrograph of virions, negatively stained withuranyl acetate. Scale bar = 100 nm. | |
Virus classification | |
| (unranked): | Virus |
| Family: | Halspiviridae |
| Genus: | Salterprovirus |
| Species | |
| |
  | |
| Locality of isolation: saltern crystalliser inAvalon, Victoria, Australia | |
| Synonyms | |
Salterprovirus
Salterprovirus His1
| |
Halspiviridae is a family of viruses that consists of a single genus,Salterprovirus, which consists of a single recognised species; Halovirus His1 (His1,Salterprovirus australiense). This virus was isolated from hypersaline water in Australia and was able to be cultured on the halophilicarchaeonHaloarcula hispanica. Like many other archaeoviruses, His1 has an approximately limoniform (lemon-shaped)virion.[1][2][3][4]
The family name,Halspiviridae, is derived fromhalophilic andspindle-shaped, in reference to the habitat and virion morphology, respectively. The genus name,Salterprovirus, is derived fromsaltyterminalproteinvirus, as the linear dsDNA genome has proteins attached to the5′ termini.[1]
The virion has a spindle-shaped morphology and is similar in shape to that of viruses infecting thermophilic archaea, theFuselloviridae, and His1 was originally described as a probable member of that group.[1] 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, genusSalterprovirus within the familyHalspiviridae.[5]Halspiviridae has not been classified within any higher-ranked taxa.[6]
Environmental DNA sequences derived fromNamib salt pans indicate the presence of currently unrecognised, distant relatives of His1.[7]
Another species of virus, now namedGammapleolipovirus His2 (hereafter 'His2'), was originally considered to be related to His1,[2][3] but later analysis of the His2 virion revealed that this species actually belongs to the familyPleolipoviridae.[8]
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.[3] 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),[9] who gave average dimensions of 92 x 40 nm with a 12 nm tail.
| Structure | Capsid | Genomic arrangement | Genomic segmentation |
|---|---|---|---|
| Limoniform | Protein | Linear | Monopartite |
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 10−12 ml min−1 has been experimentally determined by Pietilä et al. (2013).[10] DNA-templated transcription is the method of transcription.Haloarcula hispanica may serve as a host. Transmission occurs via passive diffusion.[3]
| Host details | Tissue tropism | Entry details | Release details | Replication site | Assembly site | Transmission |
|---|---|---|---|---|---|---|
| Archea:Haloarcula hispanica | None | Injection | Lytic | Cytoplasm | Cytoplasm | Passive diffusion |
| Genome size | 14,464nucleotides |
|---|---|
| Year of completion | 2020 |
The linear, dsDNA genome of His1 consists of14,464 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.[2]
