Megavirus
is a
viral
Viral means "relating to viruses" (small infectious agents).
Viral may also refer to:
Viral behavior, or virality
Memetic behavior likened that of a virus, for example:
* Viral marketing, the use of existing social networks to spread a marke ...
genus containing a single identified species named ''Megavirus chilensis'', phylogenetically related to Acanthamoeba polyphaga
Mimivirus (APMV).
In colloquial speech, Megavirus chilensis is more commonly referred to as just “Megavirus”. Until the discovery of
pandoraviruses in 2013, it had the largest
capsid diameter of all known viruses, as well as the largest and most complex
genome among all known viruses.
Discovery
Megavirus was isolated from a water sample collected in April 2010 off the coast of
Chile, near the marine station in Las Cruces, by Jean-Michel Claverie and Chantal Abergel from the Structural & Genomic Information laboratory (IGS, CNRS and Aix-Marseille University). Megavirus was isolated by co-cultivation with a variety of ''
Acanthamoeba'' laboratory strains (''
A. polyphaga'', ''
A. castellanii'', ''
A. griffini'') following a protocol pioneered by Timothy Rowbotham for isolating intracellular parasitic bacteria.
Megavirus infects amoebas.
Structure
The Megavirus particle exhibits a protein
capsid diameter of 440
nanometre
330px, Different lengths as in respect to the molecular scale.
The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American and British English spelling differences#-re ...
s (as seen by electron microscopy on thin sections of epoxy resin inclusions), enclosed into a solid mesh of bacterial-like capsular material 75 nm to 100 nm thick. The capsid appears hexagonal, but its icosahedral symmetry is imperfect, due to the presence of the “stargate”, at a single specific vertex of the icosahedron. The stargate is a five-pronged star structure forming the portal through which the internal core of the particle is delivered to the host's cytoplasm. This core is enclosed within two lipid membranes in the particle, also containing a large and diverse complement of viral proteins (e.g. the all transcriptional complex). Surprisingly, the Megavirus is larger than some bacteria.
Genome
The Megavirus chilensis genome is a linear, double-stranded molecule of
DNA with 1,259,197
base pairs
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...
in length. It exhibits 7
aminoacyl tRNA synthetases
An aminoacyl-tRNA synthetase (aaRS or ARS), also called tRNA-ligase, is an enzyme that attaches the appropriate amino acid onto its corresponding tRNA. It does so by catalyzing the transesterification of a specific cognate amino acid or its pre ...
(Table 2), the archetypes of enzymes previously thought only to be encoded by cellular organisms. While 4 of these enzymes were known to be present in Mimivirus and Mamavirus (for tyrosine, arginine, cysteine, and methionine), Megavirus exhibits three more (for tryptophan, asparagine, and isoleucine).
See also
*
Mimivirus – the giant virus that revolutionized virology
*
Cafeteria roenbergensis virus
''Cafeteria roenbergensis virus'' (CroV) is a giant virus that infects the marine bicosoecid flagellate ''Cafeteria roenbergensis'', a member of the microzooplankton community.
History
The virus was isolated from seawater samples collected from ...
– the largest marine virus
*
Parvovirus – smallest known single stranded DNA
viruses
*
Pithovirus - largest virus by capsid length (approximately 1.5
micrometre)
*
Pandoraviridae - second largest virus by capsid length (approximately 1 micrometre)
*
Virophage
References
External links
GiantVirus.org– an information resource on the genome of giant viruses.
International Committee on Taxonomy of Viruses (ICTV) picture gallery- images of mimivirus
*
{{Taxonbar, from=Q285598
Mimiviridae