Coccolithovirus
| Coccolithovirus | |
|---|---|
| Virus classification | |
| Group: | Group I (dsDNA) |
| Family: | Phycodnaviridae |
| Genus: | Coccolithovirus |
| Type Species | |
| |
Coccolithovirus is a genus of giant double-stranded DNA virus, in the family Phycodnaviridae. Alga, specifically Emiliania huxleyi, a species of coccolithophore, serve as natural hosts. There are currently only one species in this genus: the type species Emiliania huxleyi virus 86.[1][2]
Taxonomy
Group: dsDNA
- Family: Phycodnaviridae
- Genus: Coccolithovirus
- Emiliania huxleyi virus 86
Structure
Viruses in Coccolithovirus are enveloped, with icosahedral and Round geometries, and T=169 symmetry. The diameter is around 100-220 nm. Genomes are linear, around 410-415kb in length. The genome codes for 472 proteins.[1]
| Genus | Structure | Symmetry | Capsid | Genomic Arrangement | Genomic Segmentation |
|---|---|---|---|---|---|
| Coccolithovirus | Icosahedral | T=169 | Enveloped | Linear | Monopartite |
Life Cycle
Viral replication is nucleo-cytoplasmic. Replication follows the DNA strand displacement model. Dna templated transcription is the method of transcription. The virus exits the host cell by lysis via lytic phospholipids. Alga serve as the natural host. Transmission routes are passive diffusion.[1]
| Genus | Host Details | Tissue Tropism | Entry Details | Release Details | Replication Site | Assembly Site | Transmission |
|---|---|---|---|---|---|---|---|
| Coccolithovirus | Alga | None | Cell receptor endocytosis | Budding | Nucleus | Cytoplasm | Passive diffusion |
Genomes
Two genomes have been sequenced Emiliania huxleyi virus 86 and Emiliania huxleyi virus 203.[3] The genomes are ~400 kilobase pairs in length with a G+C content of 41.1% and contains ~470 predicted coding sequences. A third genome has been partly sequenced.[4] A fourth genome - that of Emiliania huxleyi virus 84 - has also been sequenced.[3] A fifth virus 202 has also been sequenced.[5] A further four genomes have also been sequenced.[5]
Another virus (EhV-99B1) has been isolated from a Norwegian fjord has been sequenced.[6]
History
Wilson and his team at the Marine Biological Association (MBA), University of East Anglia and Plymouth Marine Laboratory (PML), first observed the virus in 1999. Later in the summer of 2005 researchers at the Plymouth Marine Laboratory (Willie Wilson et al.) and at the Sanger Institute (Holden et al.) sequenced the genome for the EhV-86 strain finding it to have 472 protein-coding genes making it a "giant-virus", and the largest known marine virus by genome.
From initial investigation of the Coccolithoviruses genome, a sequence of genes responsible for production of ceramide was discovered . Ceramide is a controlling factor in cell death, and it is currently thought that Coccolithovirus uses this to prolong the life of Emiliania huxleyi while it uses the host cell to replicate. This is a unique ability unseen in any other viral genome to date.
See also
- Mimivirus - largest giant virus on record by genome
- Mycoplasma genitalium, Pelagibacter ubique - some of the smallest known bacteria
- Nanoarchaeum - smallest known archaeum
- Smallest organisms
- Parvovirus - smallest known family of viruses
- Phycodnaviridae - algae infecting viruses
Notes
References
- 1 2 3 "Viral Zone". ExPASy. Retrieved 15 June 2015.
- 1 2 ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
- 1 2 Nissimov JI, Worthy CA, Rooks P, Napier JA, Kimmance SA, Henn MR, Ogata H, Allen MJ (2011) Draft genome sequence of the Coccolithovirus Emiliania huxleyi Virus 203. J Virol 85(24):13468-13469
- ↑ Allen MJ, Schroeder DC, Donkin A, Crawfurd KJ, Wilson WH (2006) Genome comparison of two Coccolithoviruses. Virol J 22;3:15
- 1 2 Nissimov JI, Worthy CA, Rooks P, Napier JA, Kimmance SA, Henn MR, Ogata H, Allen MJ (2012) Draft genome sequence of the Coccolithovirus Emiliania huxleyi virus 202. J Virol 86(4):2380-2381
- ↑ Pagarete A, Lanzén A, Puntervoll P, Sandaa RA, Larsen A, Larsen JB, Allen MJ, Bratbak G (2012) Genomic sequence and analysis of EhV-99B1, a new coccolithovirus from the Norwegian fjords. Intervirology
Further reading
- Wilson, W. H., Schroeder, D. C., Allen, M. J., Holden, M. T. G., Parkhill, J., Barrell, B. G., Churcher, C., Hamlin, N., Mungall, K., Norbertczak, H., Quail, M. A., Price, C., Rabbinowitsch, E., Walker, D., Craigon, M., Roy, D. and Ghazal, P. (2005) Complete Genome Sequence and Lytic Phase Transcription Profile of a Coccolithovirus. Science 5737, 1090-1092
- Allen, M. J., Schroeder, D. C., Holden, M. T. and Wilson, W. H. (2006) Evolutionary History of the Coccolithoviridae. Mol Biol Evol. 23, 86-92 (Athens login required)