Giant virus
A giant virus is a very large virus. They are sometimes called a girus. Some of them are larger than typical bacteria.[1][2] All known giant viruses belong to the phylum Nucleocytoviricota.[3]
| Megaviricetes | |
|---|---|
| |
| Mimivirus | |
Virus classification 
| |
| Unrecognized taxon (fix): | Megaviricetes |
The genomes of many giant viruses code for unusual genes which are not found in other viruses. These include genes involved in glycolysis and the TCA cycle,[4] fermentation,[5] and the cytoskeleton.[6][7][8]
The first giant viruses to be described were discovered in 1981.[9]
Note, in the illustration from an electron microscope, the virus is surrounded by a thick (~100 nm) layer of filamentous protein fibres.
Origin
There are two main hypotheses. Either they evolved from small viruses by picking up DNA from host organisms; or they evolved from very complicated organisms by genome reduction.[10]
Giant Virus Media
Phylogeny of Nucleocytoviricota
References
- ↑ Reynolds, Kelly A.. Mysterious microbe in water challenges the very definition of a virus. Water Conditioning & Purification (2010).
- ↑ Remarkable sequence similarity between the dinoflagellate-infecting marine girus and the terrestrial pathogen African swine fever virus. Virology Journal 6 (178) (October 2009). p. 178. doi:10.1186/1743-422X-6-178.
- ↑ Van Etten, James L.. Giant Viruses. American Scientist 99 (4) (July–August 2011). p. 304–311. doi:10.1511/2011.91.304.
- ↑ Dynamic genome evolution and complex virocell metabolism of globally-distributed giant viruses. Nature Communications 11 (1710) (2020). p. 1710. doi:10.1038/s41467-020-15507-2.
- ↑ A giant virus infecting green algae encodes key fermentation genes. Virology 518 (2018). p. 423–433. doi:10.1016/j.virol.2018.03.010.
- ↑ Giant viruses encode novel types of actins possibly related to the origin of eukaryotic actin: the viractins. bioRxiv (2020). doi:10.1101/2020.06.16.150565.
- ↑ High Transcriptional Activity and Diverse Functional Repertoires of Hundreds of Giant Viruses in a Coastal Marine System. mSystems 6 (4) (2021). p. e0029321. doi:10.1128/mSystems.00293-21.
- ↑ Discovery of Viral Myosin Genes With Complex Evolutionary History Within Plankton. Frontiers in Microbiology 12 (7 June 2021). p. 683294. doi:10.3389/fmicb.2021.683294.
- ↑ Meints, Russel H.. Viral infection of the symbiotic chlorella-like alga present in Hydra viridis. Virology 113 (2) (September 1981). p. 698–703. doi:10.1016/0042-6822(81)90198-7.
- ↑ Bichell, Rae Ellen. "In giant virus genes, hints about their mysterious origin". All Things Considered. https://www.npr.org/sections/health-shots/2017/04/06/522478901/in-giant-virus-genes-hints-about-their-mysterious-origin.