Pandoravirus

Source: Wikipedia, the free encyclopedia.


Pandoravirus
Virus classification
Group:
Group I (
dsDNA
)
Order:
Megavirales
Family:
Pandoraviridae
Genus:
Pandoravirus
Species

Pandoravirus is a

giant virus, first discovered in 2013.[5] It is the second largest in physical size of any known viral genus, behind only Pithovirus.[6] Pandoraviruses have double stranded DNA genomes, with the largest genome size (2.5 million base pairs) of any known viral genus.[7]

Discovery

The discovery of Pandoraviruses by a team of French scientists, led by husband and wife Jean-Michel Claverie and Chantal Abergel, was announced in a report in the journal Science in July 2013.[5] Other scientists had previously observed the pandoravirus particles, but owing to their enormous size they were not expected to be viruses.[5] Patrick Scheid, a parasitologist from the Central Institute of the Bundeswehr Medical Service in Koblenz, Germany, found one in 2008, in an amoeba living in the contact lens of a woman with keratitis. Its development within the amoebal host was documented extensively. Unlike in other cases with such giant viruses, the large particles within Acanthamoeba were not mistaken for bacteria. The authors initially termed them "endocytobionts".[8]

Mimivirus, a nucleocytoplasmic large DNA virus with a genome size of about 1.1 megabases, was described in 1992 but not recognized as a virus until 2003.[9] Megavirus, discovered in seawater off the coast of Chile in 2011, has a genome size of approximately 1.2 megabases.[10]

The prior discovery of these viruses prompted a search for other types of large amoeba-infecting viruses, which led to the finding of two species;

Melbourne, Australia, with a 1.9 megabase genome.[5][11]

Description

Pandoraviruses are oval in shape and are about 1 micrometer (1000 nanometers) in length. Other viruses range from 25 to 100 nanometers. In addition to being large physically, Pandoraviruses have a large genome made up of 2,500 genes, compared to only 10 genes on average in other viruses. For example, the Influenza A virus contains 7 genes and HIV contains only 9 genes. Gene content varies among species of Pandoravirus, with Pandoravirus salinus containing 2,500 genes and Pandoravirus dulcis containing about 1,500 genes. Pandoraviruses were originally mistaken for bacteria; however, they lack some of the characteristics of bacteria, such as the ability to make their own proteins. The dissimilarity of the remaining genes to any cellular genes led researchers to speculate that this virus represents a previously unknown branch of the  tree of life. However, other experts have called this proposal premature because there is very little evidence supporting the idea.[12]

Replication

Pandoraviruses have double stranded DNA. Like most giant viruses, Pandoraviruses have a viral life cycle. They lack the ability to make their own proteins, rely on the host cells for ATP (energy) and reproduction, and also do not contain ribosomes or produce energy to divide. Under the microscope, scientists observed the virus enter the amoeba through fusion with membrane vacuoles, and integrate their DNA into the host cells. The host cell replicates the viral particles and eventually splits open, releasing the viral particles. The process of replication lasts 10–15 hours.[13] Viral replication and assembly happens simultaneously. In other words, viral DNA is replicated within the cytoplasm of the host cell and assembled into new viral particles followed by lysis of the host cell.[14]

Prevalence in the environment

Pandoraviruses do not seem to be harmful to humans. They are mostly found in marine environments, infecting amoebae. One reason for their only relatively recent discovery is because they exist in environments that are not well studied. Pandoraviruses, like other marine viruses, prey on plankton, which are organisms that live in the water column and form the basis of the food chain for other marine species. More study and research needs to be done in order to confirm the prevalence of Pandoraviruses in different environments. Currently, not much is known about their role in marine ecosystems. however, viruses are not mere pathogens for their host, but are also key players in aquatic ecosystems and the biosphere. Almost all genomes of cellular organisms contain viral sequences, elements of which are also essential in gene regulation. Viral infection and lysis can influence community structure, as well as the transfer of matter and energy in aquatic ecosystems. They can also dramatically alter host physiology through viral gene expression and drive evolutionary innovation through virus-mediated horizontal gene transfer. [15]

Phylogenetic affinities

Approximately 93% of Pandoravirus genes are not known from any other microbes,[16] suggesting that they belong to an as of yet undescribed "fourth domain" aside from Bacteria, Archaea, and Eukaryotes.[16] Viruses are not widely considered to belong within these three domains, although they have been proposed as one in the past by some biologists.[17]

Comparison with other giant viruses

Other giant viruses such as the Mimivirus,

phagocytic vacuoles, then fuses with the membrane vacuole of the amoeba. This leads to viral particles to be released into the cytoplasm of the amoeba.[19]

See also

References

  1. ^ "Pandoravirus dulcis". NCBI Taxonomy Browser. 1349409. Archived from the original on 2017-08-31. Retrieved 2017-09-07.
  2. ^ "Pandoravirus salinus". NCBI Taxonomy Browser. 1349410. Archived from the original on 2017-06-20. Retrieved 2017-09-07.
  3. ^ "Pandoravirus tropicalis". NCBI Taxonomy Browser. Archived from the original on 2022-12-14. Retrieved 2022-12-14.
  4. ^ "'Zombie' virus revived after 50,000 years trapped in Siberian permafrost - National | Globalnews.ca". Global News. Archived from the original on 2022-11-26. Retrieved 2022-11-26.
  5. ^
    S2CID 16877147. Archived
    (PDF) from the original on 2020-04-02. Retrieved 2020-03-05.
  6. ^ Sirucek S (3 March 2014). "Ancient "Giant Virus" Revived From Siberian Permafrost". National Geographic. Archived from the original on 4 March 2014.
  7. S2CID 87146458
    .
  8. S2CID 20548450
    .
  9. S2CID 39606235
    .
  10. PMID 21987820
    .
  11. ^ Smith B (26 July 2013). "Pandoravirus discovered in La Trobe uni pond". The Age. Archived from the original on 20 August 2013. Retrieved 18 August 2013.
  12. ^ "Pandoraviruses Are Not Alive". www.virology.ws. 3 December 2020. Archived from the original on 2021-09-12. Retrieved 2021-09-19.
  13. ^ "Pandoravirus, bigger and unlike anything seen before". www.virology.ws. August 2013. Archived from the original on 2017-11-18. Retrieved 2017-11-25.
  14. PMID 30541841
    .
  15. ISSN 2772-7351
    .
  16. ^ a b Dell'Amore C (19 July 2013). "Biggest Virus Yet Found, May Be Fourth Domain of Life?". National Geographic. Archived from the original on July 21, 2013. Retrieved 20 March 2018.
  17. ^ Berezow AB (16 November 2014). "Simmer Down: Viruses Not 'Fourth Domain' of Life | RealClearScience". realclearscience. Archived from the original on 20 March 2018. Retrieved 20 March 2018.
  18. ^ "What Is an Amoeba?". Live Science. Archived from the original on 2017-10-12. Retrieved 2017-11-10.
  19. ^ "Pandoravirus, bigger and unlike anything seen before". www.virology.ws. August 2013. Archived from the original on 2017-11-18. Retrieved 2017-11-10.

External links

Wikispecies has information related to Pandoravirus.