Megavirus

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' Megavirus'
Megavirus.jpg

' Megavirus'

Systematics
Classification : Viruses
Area : Varidnaviria
Empire : Bamfordvirae
Phylum : Nucleocytoviricota
Class : Megaviricetes
Order : Impersonal
Family : Mimiviridae (syn. Megaviridae )
Subfamily : "Mimivirinae" / "Megavirinae" / "Megamimivirinae"
Genre : Mimivirus
without rank: "Mimivirus Line C "
Type : Megavirus chilensis
Taxonomic characteristics
Genome : dsDNA
Baltimore : Group 1
Symmetry : imperfectly icosahedral
Cover : available
Scientific name
Megavirus
Short name
MGV
Left
NCBI  Taxonomy: 1094892

The megaviruses are a proposed group of DNA viruses , the first representative of which, the species Megavirus chilensis (often incorrectly called Megavirus chiliensis ; acronym MGVC , also MVc ) was discovered by French scientists off the coast of Chile in 2010 . The virus is a distant relative of Acanthamoeba polyphaga mimivirus (APMV) and is believed to infect acanthamoeba . The National Center for Biotechnology Information (NCBI) assigns the species Megavirus chilensis to the genus Mimivirus , but because of the relatively distant relationship, a preliminary genus Megavirus (MGV) could also be considered. Within the family of Mimiviridae , the megaviruses of group I (proposed subfamily Mimivirinae or Megamimivirinae ) are assigned. This group is proposed to be divided into different lines, with line C (also Courdo11 group) corresponding to the megaviruses.

discovery

Megavirus chilensis was isolated from seawater collected in April 2010 off the coast of Chile near Las Cruces by Jean-Michel Claverie and Chantal Abergel from the University of Aix-Marseille . Scientists from this laboratory were also involved in characterizing the mimivirus . The virus was at the co-cultivation of a number of Acanthamoeba isolated strains, from the species ( Acanthamoeba polyphaga , A. castellanii and A. Griffini ). A method was used that had been developed by Timothy Rowbotham for the isolation of intracellular parasitic bacteria. The natural host of the MGVC is believed to be a phagocytic protozoon that lives in sea or brackish water .

structure

The virions (virus particles) of the MGVC consist of a protein capsid with a diameter of 440  nm . They almost reach the size of small bacteria and are among the largest viruses described. The virions are surrounded by a multi-layered tegument material with a thickness of 75 to 100 nm (see Mimivirus protein filaments ). The capsid appears hexagonal , but its icosahedral symmetry is not perfect because it contains at least one so-called “stargate”. A “stargate” is a structure that resembles a five-pointed star and that forms an opening through which the core material of the virus enters the host's cytoplasm (see Mimivirus §Stargate ). The capsid is surrounded by two membranes that contain different viral proteins.

Genome

The genome of MGVC consists of a linear double-stranded DNA with a length of 1,259,197 base pairs . At the time of its discovery it was the largest known virus genome. It is 67.5 kb larger than the genome of the mimivirus and probably contains 1120 coding regions (i.e., coded proteins ), which is more than many bacteria. The GC content is 25%.

The MGVC has seven aminoacyl-tRNA synthetases , enzymes that usually only occur in cellular organisms. Four of these proteins are also known from the Acanthamoeba polyphaga mimivirus (ApMV) and the Acanthamoeba castellanii mamavirus (ACMV) (those for the amino acids tyrosine , arginine , cysteine and methionine ). MGVC also contains the aminoacyl-tRNA synthetases for tryptophan , asparagine and isoleucine . The Cafeteria roenbergensis virus (CroV) only contains the aminoacyl-tRNA synthetase for isoleucine. The MGVC also contains the gene for a special variant of the mismatch repair enzyme MutS, which is otherwise only found in the mitochondria of Octocorallia . This MutS version appears to be found only in members of the Mimiviridae family. Like ApMV, MGVC contains genes for the metabolism of sugars , fats and amino acids .

The MGVC and the ApMV share 594 orthologous genes . Most of these matching genes are located in the middle of the viral genomes, each flanked by species-specific sections in the 5 'and 3' area. With regard to the amino acid sequences , the proteins encoded by these orthologous genes are approximately 50% identical.

Analysis of the MGVC's viral genome indicated that mimiviruses and megaviruses (i.e., lines A and C) might descend from a common ancestor, derived from reductive evolution from parts of a cellular genome.

Replication

The replication stages of MGVC are similar to those of the mimivirus. Shortly after phagocytosis and the release of the inner capsid into the cytoplasm of the host cell, the eclipse phase begins . So-called cytoplasmic "seeds" are found, which correspond in size to the megavirus core. These seeds develop into virion factories within 14 hours . Until the lysis of the amoeba cell and the release of the virus during MGVC usually it takes about 17 hours (as opposed to about 12 hours when Mimivirus). Approx. 500 new viruses are produced per infected cell - in contrast to 1000 particles in Acanthamoeba polyhaga mimivirus (ApMV).

MGVC thus belongs to a non-taxonomic group of large cytoplasmic viruses known as nucleocytoplasmic large DNA viruses (NCLDV, proposed virus order ' Megavirales '). A classification feature of this group is the fact that they reproduce completely in the host's cytoplasm with the help of so-called large virion factories without replicating the double-stranded DNA (as is usually the case with ds-DNA viruses) with the help of the host's own DNA polymerases in the host cell's nucleus .

Meaning of discovery

Two properties of MGVC are important: Although it is only 6% larger than ApMV, one could already assume when it was discovered that it is not the largest virus. The fact that three other aminoacyl-tRNA synthetases were found in viral genomes suggested that these enzymes were not acquired from other viruses by lateral gene transfer . Analysis of their sequence indicates relationship to eukaryotic genes. Based on this, it was assumed that the genome of these viruses could have arisen from the genome of a cellular organism through genome reduction, similar to that of other parasites . It was also assumed that megaviruses are evolutionarily very old, and that they may be older than today's eukaryotes. They could then have arisen at the same time as the nucleus ; a conjecture supported by the similarity of the cell nucleus to the virus factory mentioned above. Another assumption is that megaviruses originate from a cellular domain that has since become extinct . However, these views have also been contradicted, arguing that the NCLDV acquired their size independently on multiple lines through the acquisition of genes via horizontal gene transfer . The discovery of Medusavirus , however, raised the question again.

Systematics

Neither Megavirus chilensis nor the group of megaviruses (Line C) have been confirmed by the International Committee on Taxonomy of Viruses (ICTV) as of March 2019 .

Presumably, these candidates will be described as members of the ICTV confirmed family Mimiviridae (outdated also " Megaviridae "). Viruses that are sufficiently similar in structure and sequence to Avcanthamoeba polypahaga mimivirus (ApMV) and MGVC ( Mimiviridae group I) will probably belong to the family . Within this group, the megaviruses were suggested as line C (alias Courdo11 group) due to their particularly strong genetic similarity. A number of candidates have been suggested by Andreani et al. Proposed in 2018. The NCBI lists the following candidates in the species “ Megavirus chilensis ” (written there as well as by S. Barik and other authors “ Megavirus chiliensis ”) (internal systematics):

  • Species: " Megavirus chilensis "
  • Megavirus courdo11 (alias Courdo11 virus, namesake of the line) with Courdo Virus CE11
  • Megavirus lba (aka Megavirus LBA111, LBA111 virus)
  • Terra1 megavirus (aka Terra1 virus)
  • Powai lake megavirus (PLMV, alias Powai Lake Virus)

The NCBI leads u. a. as an independent sister species of MGVC among the megaviruses, the following candidates (external systematics):

  • Species: " Megavirus avenue9 "
  • Species: " Megavirus balcon "
  • Species: " Megavirus battle43 "
  • Species: " Megavirus bus " (aka Mimivirus bus )
  • Species: " Megavirus courdo5 "
  • Species: " Megavirus courdo7 "
  • Species: " Megavirus feuillage "
  • Species: " Megavirus mont1 "
  • Species: " Megavirus J3 "
  • Species: " Megavirus montpellier " (aka " Megavirus montpellier3 ")
  • Species: " Megavirus potager "
  • Species: " Megavirus ursino "
  • Species: " Megavirus shan " (aka " Shan virus ")
  • Species: " Megavirus T1 "
  • Species: " Megavirus T4 "
  • Species: " Megavirus T6 "
  • Species: " Megavirus vitis "
  • Species: " Bandra megavirus " (BMV)
  • Species: " Afrovirus urmite69 "

Proposed phylogenetic tree of the genus Mimivirus according to Abrahão et al. (2018), Fig. 4:

 Mimivirus 

" Mimivirus group A" (" Mimivirus s. S. ")


   

" Mimivirus group B" (" Moumouvirus group")


 " Mimivirus group C"
( Courdo11 group ) 

" Courdo7 virus "


  


Terra1 virus


   

Powai lake Megavirus



   

Courdo11 virus


   

" Megavirus chilensis " (wild type)


   

LBA111 virus








Template: Klade / Maintenance / Style

Note: Italics for suggested species.

Genome comparison with related viruses

virus Genome size ( bp ) Genes Capsid diameter ( nm ) Genebank no.
Megavirus chilensis 1,259,197 1120 proteins (derived) 440 JN258408
Mamavirus ACMV 1,191,693 1023 proteins (derived) 390 JF801956
Mimivirus ApMV
(wild type M1)		 1,181,549 979 proteins (39 non-coding) 390 NC_014649
Mimivirus M4
(soon / fiberless variant)		 981.813 756 proteins (derived) 390 JN036606
Cafeteria roenbergensis virus 617,453 (730 kbp) 544 proteins (derived) 300 NC_014637

Features of the Mimiviridae in comparison

virus Aminoacyl-tRNA synthetase Octocorallia -like MutS Protein filaments (length) Stargate Well-known virophage Cytoplasmic
Virion Factory 		host
Megavirus chilensis 7 ( Tyr , Arg , Met , Cys , Trp , Asn , Ile ) Yes yes (75 nm)  Yes No Yes Acanthamoeba ( Unikonta , Amoebozoa )
Mamavirus ACMV 4 (Tyr, Arg, Met, Cys) Yes yes (120 nm) Yes Yes Yes Acanthamoeba (Unikonta, Amoebozoa)
Mimivirus ApMV
(wild type M1)		 4 (Tyr, Arg, Met, Cys) Yes yes (120 nm) Yes Yes Yes Acanthamoeba (Unikonta, Amoebozoa)
Mimivirus M4
(soon / fiberless variant)		 2 (Met, Cys) No No Yes resistant Yes Acanthamoeba (Unikonta, Amoebozoa)
Cafeteria roenbergensis virus 1 (Ile) Yes No No Yes Yes Phagotrophic protozoa ( heteroconta , stramenopiles )

literature

Web links

  • GiantVirus.org - an information resource on the genome of giant viruses.

Individual evidence

  1. ↑ a b c d e f ICTV: ICTV Taxonomy history: Acanthamoeba polyphaga mimivirus , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  2. ↑ a b Christoph M. Deeg, Cheryl-Emiliane T. Chow, Curtis A. Suttle: The kinetoplastid-infecting Bodo saltans virus (BsV), a window into the most abundant giant viruses in the sea ... , in: eLife Sciences 7, March 2018, doi: 10.7554 / eLife.33014
  3. ↑ Center national de la recherche scientifique: List of the main “giant” viruses known as of today (March 2019) , Université Aix Marseille, March 2019.
  4. ↑ a b c Frederik Schulz, Lauren Alteio, Danielle Goudeau, Elizabeth M. Ryan, Feiqiao B. Yu, Rex R. Malmstrom, Jeffrey Blanchard, Tanja Woyke: Hidden diversity of soil giant viruses , in: Nature Communications Volume 9, No. 4881, November 19, 2018, doi: 10.1038 / s41467-018-07335-2
  5. ↑ a b c Defne Arslan, Matthieu Legendre, Virginie Seltzer, Chantal Abergel, Jean-Michel Claverie: Distant Mimivirus relative with a larger genome highlights the fundamental features of Megaviridae . In: PNAS . October 10, 2011, doi : 10.1073 / pnas.1110889108 .
  6. ↑ a b D. Raoult u. a .: The 1.2-Megabase Genome Sequence of Mimivirus . In: Science . tape 306 , no. 5700 , 2004, p. 1344-1350 , doi : 10.1126 / science.1101485 , PMID 15486256 .
  7. ↑ a b NCBI: Megavirus chiliensis (Tree), Megavirus chiliensis (Species)
  8. ^ TJ Rowbotham: Isolation of Legionella pneumophila from clinical specimens via amoebae, and the interaction of those and other isolates with amoebae . In: Journal of Clinical Pathology . tape 36 , no. 9 , 1983, pp. 978-986 , doi : 10.1136 / jcp.36.9.978 , PMID 6350372 , PMC 498455 (free full text).
  9. ^ A b Nathan Zauberman, Y. Mutsafi, DB Halevy, E. Shimoni, E. Klein, C. Xiao, S. Sun, A. Minsky: Distinct DNA Exit and Packaging Portals in the Virus Acanthamoeba polyphaga mimivirus . In: PLoS Biology . tape 6 , no. 5 , 2008, p. e114 , doi : 10.1371 / journal.pbio.0060114 , PMID 18479185 , PMC 2430901 (free full text).
  10. ↑ David M. Needham, Alexandra Z. Worden et al .: A distinct lineage of giant viruses brings a rhodopsin photosystem to unicellular marine predators , in: PNAS, 23 September 2019, doi: 10.1073 / pnas.1907517116 , ISSN 0027-8424 , here: Supplement 1 (xlsx)
  11. ↑ Hiroyuki Ogata, J. Ray, K. Toyoda, RA Sandaa, K. Nagasaki, G. Bratbak, JM Claverie: Two new subfamilies of DNA mismatch repair proteins (MutS) specifically abundant in the marine environment . In: The ISME Journal . tape 5 , no. 7 , 2011, p. 1143–1151 , doi : 10.1038 / ismej.2010.210 , PMID 21248859 , PMC 3146287 (free full text).
  12. ↑ Jean-Michel Claverie, Chantal Abergel: Mimivirus: The emerging paradox of quasi-autonomous viruses . In: Trends in Genetics . tape 26 , no. 10 , 2010, p. 431–437 , doi : 10.1016 / j.tig.2010.07.003 , PMID 20696492 .
  13. ↑ M. Legendre, D. Arslan, C. Abergel, JM Claverie: Genomics of Megavirus and the elusive fourth domain of Life. , in: Commun Integr Biol. 5 (1), January 1, 2012, pp. 102-106, PMID 22482024 .
  14. ↑ Gwyneth Dickey Zakaib: The challenge of microbial diversity: Out on a limb . In: Nature . tape 476 , no. 7358 , 2011, p. 20-21 , doi : 10.1038 / 476020a , PMID 21814255 .
  15. ↑ Natalya Yutin, Eugene V Koonin: Hidden evolutionary complexity of Nucleo-Cytoplasmic Large DNA viruses of eukaryotes , in: Virology Journal, Volume 9, No. 161, August 14, 2012, doi: 10.1186 / 1743-422X-9-161
  16. ↑ ICTV : Master Species List 2018b.v2 . Retrieved August 6, 2019. MSL # 34v
  17. ↑ a b c d e Julien Andreani, Jacques YB Khalil, Emeline Baptiste, Issam Hasni, Caroline Michelle, Didier Raoult, Anthony Levasseur, Bernard La Scola: Orpheovirus IHUMI-LCC2: A New Virus among the Giant Viruses , in: Front. Microbiol., January 22, 2018, doi: 10.3389 / fmicb.2017.02643
  18. ↑ a b c Sailen Barik: A Family of Novel Cyclophilins, Conserved in the Mimivirus Genus of the Giant DNA Viruses , in: Computational and Structural Biotechnology Journal, Volume 16, July 2018, pp. 231-236, doi: 10.1016 / j. csbj.2018.07.001
  19. ↑ a b Julien Guglielmini, Anthony C. Woo, Mart Krupovic, Patrick Forterre, Morgan Gaia: [1] , in: PNAS 116 (39), 10./24. September 2019, pp. 19585-19592, doi: 10.1073 / pnas.1912006116 , PMID 31506349 , Fig. 2
  20. ↑ Eugene V. Koonin, Natalya Yutin: Multiple evolutionary origins of giant viruses , in: F1000 Research, November 22, 2018, doi: 10.12688 / f1000research.16248.1 , version 1
  21. ↑ a b c Morgan Gaia, Samia Benamar, Mondher Boughalmi, Isabelle Pagnier, Olivier Croce, Philippe Colson, Didier Raoult, Bernard La Scola: Zamilon, a Novel Virophage with Mimiviridae Host Specificity . In: PLoS One . 9 (4), 2014, p. E94923. doi : 10.1371 / journal.pone.0094923 . PMID 24747414 . PMC 3991649 (free full text). Published online April 18, 2014
  22. ↑ a b c d e f g h i j k l m n o p q Didier Raoult, Anthony Levasseur, Bernard La Scola: PCR Detection of Mimivirus, in: Emerging Infectious Diseases, June 2017, Vol. 23, No. 6, Pp. 1044-1045, doi: https: //dx.doi.org/10.3201/eid2306.161896 , PDF
  23. ↑ NCBI: Courdo virus CE11
  24. ↑ Clara Rolland, Julien Andreani, Amina Cherif Louazani, Sarah Aherfi, Rania Francis, Rodrigo Rodrigues, Ludmila Santos Silva, Dehia Sahmi, Said Mougari, Nisrine Chelkha, Meriem Bekliz, Lorena Silva, Felipe Assis, Fábio Dornas, Jacques Yaacoub Bou Khalil, Isabelle Pagnier, Christelle Desnues, Anthony Levasseur, Philippe Colson, Jônatas Abrahão, Bernard La Scola: Discovery and Further Studies on Giant Viruses at the IHU Mediterranee Infection That Modified the Perception of the Virosphere , in: Viruses 11 (4), March / April 2019, pii: E312, doi: 10.3390 / v11040312 , PMC 6520786 (free full text), PMID 30935049 , see Tab. 1
  25. ↑ NCBI: LBA111 (isolates)
  26. ↑ a b Hanene Saadi, Dorine-Gaelle Ikanga Reteno, Philippe Colson, Sarah Aherfi, Philippe Minodier, Isabelle Pagnier, Didier Raoult, Bernard La Scola: Shan Virus: A New Mimivirus Isolated from the Stool of a Tunisian Patient with Pneumonia , in: Intervirology 2013 No. 56, pp. 424-429, doi: 10.1159 / 000354564
  27. ↑ a b Hansika Chhabra: Giant viruses found in water samples from Mumbai , in: BusinessLine: Science, Bangalore, May 9, 2019
  28. ↑ Anirvan Chatterjee et al. : Complete Genome Sequence of a New Megavirus Family Member Isolated from an Inland Water Lake for the First Time in India , in: Microbiology Resource Announcements, 2016, doi: 10.1128 / genomeA.00402-16
  29. ↑ NCBI: Megavirus avenue9 (Species)
  30. ↑ NCBI: Megavirus balcon (Species)
  31. ↑ NCBI: Megavirus battle43 (Species)
  32. ↑ NCBI: Megavirus bus (Species)
  33. ↑ a b Jônatas Abrahão, Lorena Silva, Ludmila Santos Silva, Jacques Yaacoub Bou Khalil, Rodrigo Rodrigues, Thalita Arantes, Felipe Assis, Paulo Boratto, Miguel Andrade, Erna Geessien Kroon, Bergmann Ribeiro, Ivan Bergier, Herve Seligmann, Eric Ghigo, Philippe Colson, Anthony Levasseur, Guido Kroemer, Didier Raoult, Bernard La Scola: Tailed giant Tupanvirus possesses the most complete translational apparatus of the known virosphere . In: Nature Communications . 9, No. 1, February 27, 2018. doi : 10.1038 / s41467-018-03168-1 .
  34. ↑ Anirvan Chatterjee, Thomas Sicherheitsitz-Pontén, Rajesh Yadav, Kiran Kondabagil: Isolation and complete genome sequencing of Mimivirus bombay, a Giant Virus in sewage of Mumbai, India , in: Genomics Data 9 (C), May 2016, doi: 10.1016 / j.gdata.2016.05.013 , Fig. 2
  35. ↑ NCBI: Megavirus courdo5 (Species)
  36. ↑ NCBI: Megavirus courdo7 (Species)
  37. ↑ NCBI: Megavirus feuillage (Species)
  38. ↑ NCBI: Megavirus mont1 (species)
  39. ↑ NCBI: Megavirus J36 (species)
  40. ↑ NCBI: Megavirus montpellier (species)
  41. ↑ NCBI: Megavirus potager (species)
  42. ↑ NCBI: Megavirus ursino (species)
  43. ↑ NCBI: Megavirus shan (species)
  44. ↑ NCBI: Megavirus T1 (species)
  45. ↑ NCBI: Megavirus T4 (species)
  46. ↑ NCBI: Megavirus T6 (species)
  47. ↑ NCBI: Megavirus vitis (species)
  48. ↑ NCBI: Bandra megavirus (species)
  49. ↑ NCBI: Afrovirus urmite69 (Species)
  50. ↑ Anthony Levasseur, Meriem Bekliz, Eric Chabrière, Pierre Pontarotti, Bernard La Scola, Didier Raoult: MIMIVIRE is a defense system in Mimivirus did confers resistance to virophage. In: Nature , 2016, doi: 10.1038 / nature17146 , Supplementary Information (PDF)
  51. ↑ P. Colson et al. a .: Viruses with More Than 1,000 Genes: Mamavirus, a New Acanthamoeba polyphaga mimivirus Strain, and Reannotation of Mimivirus Genes . In: Genome Biology and Evolution . tape 3 , 2011, p. 737-742 , doi : 10.1093 / gbe / evr048 , PMID 21705471 , PMC 3163472 (free full text).
  52. ^ Matthieu Legendre et al. a .: Breaking the 1000-gene barrier for Mimivirus using ultra-deep genome and transcriptome sequencing . In: Virology Journal . tape 8 , 2011, p. 99 , doi : 10.1186 / 1743-422X-8-99 , PMID 21375749 , PMC 3058096 (free full text).
  53. ↑ M. Boyer et al. a .: Mimivirus shows dramatic genome reduction after intraamoebal culture . In: Proceedings of the National Academy of Sciences . tape 108 , no. 25 , 2011, p. 10296-10301 , doi : 10.1073 / pnas.1101118108 , PMC 3121840 (free full text).
  54. ^ MG Fischer u. a .: Giant virus with a remarkable complement of genes infects marine zooplankton . In: Proceedings of the National Academy of Sciences . tape 107 , no. 45 , 2010, p. 19508–19513 , doi : 10.1073 / pnas.1007615107 , PMC 2984142 (free full text).
  55. ^ MG Fischer, CA Suttle: A Virophage at the Origin of Large DNA Transposons . In: Science . tape 332 , no. 6026 , 2011, pp. 231-234 , doi : 10.1126 / science.1199412 , PMID 21385722 .