Phycodnaviridae
| Phycodnaviruses | |
|---|---|
| Virus classification | |
| Group: | Group I (dsDNA) |
| Family: | Phycodnaviridae |
| Genera | |
|
Chlorovirus | |
Phycodnaviruses (members of the family Phycodnaviridae) are large (160 to 560 thousand base pairs), double stranded DNA viruses that infect marine or freshwater eukaryotic algae. They belong to a super-group of large viruses known as nucleocytoplasmic large DNA viruses (NCLDVs).
Virology
Phycodnaviruses have icosahedral morphology, an internal lipid membrane and replicate, completely or partly, in the cytoplasm of their host cells. The genomes range in size from 100 kilobases (kb) to >550 kb with G+C content between 40% and 50%.
Taxonomy
The taxonomy of this family was initially based on the host range: Chlorovirus infect chlorella-like green algae from terrestrial waters, whereas members of the other five genera (Coccolithovirus, Phaeovirus, Prasinovirus, Prymnesiovirus and Raphidovirus) infect marine green and brown algae. This was subsequently confirmed by analysis of their DNA polymerases.[1]
Molecular biology
Recent studies have revealed features in Phycodnavirus genomes such as sophisticated replication and transcription machineries, a novel type of potassium channel protein, genes involved in inducing apoptosis in the host genome, a sophisticated signal transduction and gene regulation system and genes for glycosylation of viral proteins.
All of the Phycodnaviruses encode a number of proteins involved in DNA replication or recombination, including a DNA-directed DNA polymerase. It is unclear if any of the Phycodnaviruses encode a fully functional replication machinery, however. They are thought to rely on host enzymes at least partially.
Evolution
This group of viruses evolved from the Iridoviridae.[2]
References
Additional reading
- Van Etten JL. Unusual life style of giant chlorella viruses. Annu Rev Genet. 2003;37:153-95. Review. PMID 14616059 Open Access version
- Van Etten JL, Meints RH. Giant viruses infecting algae. Annu Rev Microbiol. 1999;53:447-94. Review. PMID 10547698 Open Access version
- Iyer LM, Balaji S, Koonin EV, Aravind L. Evolutionary genomics of nucleo-cytoplasmic large DNA viruses. Virus Reseearch. 2006 Apr;117(1):156-84. PMID 16494962
- Raoult D, Audic S, Robert C, Abergel C, Renesto P, Ogata H, La Scola B, Suzan M, Claverie JM. The 1.2-megabase genome sequence of Mimivirus. Science. 2004 Nov 19;306(5700):1344-50. doi:10.1126/science.1101485 PMID 15486256
- World of Chlorella Viruses Home Page