Pacman virus

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"Pacman Virus"
Systematics
Classification : Viruses
Area : Varidnaviria
Empire : Bamfordvirae
Phylum : Nucleocytoviricota
Class : Pokkesviricetes
Order : Asfuvirales
Family : " Faustoviridae " / Asfarviridae
Genre : "Pacman Virus"
Taxonomic characteristics
Genome : dsDNA (linear?)
Baltimore : Group 1
Symmetry : icosahedral
(slightly irregular)
Scientific name
"Pacman Virus"
Left
NCBI  Taxonomy: 1932881

The proposed virus - genus " Pacman virus " with the only species " Pacman virus A23 " contains giant viruses of the phylum Nucleocytoviricota (formerly Nucleocytoplasmic large DN viruses , NCLDV). It is morphologically and genetically similar to two other proposed representatives of the giant viruses, the " Faustovirus " and the " Kaumoebavirus ", as well as the viruses of the Asfarviridae family with the species Asfivirus (ASFV), the causative agent of African swine fever . The Pacman viruses got their name because of their capsid shape , which is observed in the electron microscope when it turns negative : it resembles the character in the video game Pac-Man of the same name .

Pacman viruses were detected for the first time in 2017 through the joint cultivation of amoebas of the species Acanthamoeba castellanii with various environmental samples from Algeria.

So far (as of July 2019) the proposed genus “ Pacman virus ” has not yet been registered in the database of the International Committee on Taxonomy of Viruses (ICTV).

construction

The capsids of the virus particles (virions) of " Pacman virus " have an icosahedral but slightly irregular shape (which is where it gets its name from) and reach a size of about 175  nm , with the inner membrane of the virus repeating the geometry of the capsid. The genome of “ Pacman Virus ” is a double-stranded DNA molecule (dsDNA), with a length of 395,405  bp . The GC content of the genome is 33.6% and thus below that of the related viruses. The DNA genome is most likely linear rather than circular. The genome completely absent large repeats ( English large repeats ) or inverted regions ( English inverted regions ). A tRNA gene (the isoleucine tRNA gene) was also found, although related viruses do not contain tRNA genes. According to the bioinformatic data, the genome should encode 465 genes . 135 of them are related to the genes of other viruses, 45 to the genes of eukaryotes , 41 to the genes of prokaryotes (namely 38 bacterial genes and 3 archaeal genes ). According to the analysis of the gene repertoire, the closest known relative of the “ Pacman virus ” is the so far only proposed “ Faustovirus ” (also a giant virus). Common genes with other virus genera (some also proposed):

In 3 genes there are similarities (homology) to corresponding ones from Acanthamoeba castellanii and in 4 genes to slime molds of the genus Dictyostelium . 244 genes have no known homologues and only 155 genes have functional annotation .

Propagation cycle

Compared to the mimivirus , the “ Pacman virus ” multiplies extremely quickly in the same host, the amoeba cells of Acanthamoeba castellanii . The first damaged cells appear 6 hours after infection, and after a further two hours, the amoebic cells are completely lysed. Already 15 minutes after the contact of the virion with a amoeba cell virus particles in phagocytosis - vacuoles detectable and then also in the cytoplasm of the cell, but without opening the capsid. Viruses most likely interact with mitochondria located in the cytoplasm , but membrane fusion does not occur. Although empty capsids were detected in the cytoplasm, the release of DNA from the capsid has not yet been observed. Well-established virus factories appear in the host cells 3 hours after infection , but the newly formed virions are not visible until 4 hours after infection. After 6 hours the amoeba cell fills with virus particles, which sometimes even form clusters of regular geometric shape - in the whole cell or in parts at the edge of the virus factory. Lysis finally occurs 8 hours after the virus enters the cell .

A multiplication of “ Pacman virus ” in amoebas of the species Vermamoeba vermiformis or Dictyostelium discoideum was not possible.

Systematics

Based on the gene sequence of genes of the DNA polymerase B family , " Pacman virus ", " Kaumoebavirus ", " Faustovirus " and the Asfarviridae form a phylogenetic tree ( clade ), apparently these viruses had a common ancestor. With regard to the capsid architecture, “ Pacman virus ” is closest to “ Faustovirus ”.

Most authors suggest that the genus Faustovirus be regarded as the prototype of a new family Faustoviridae within the nucleocytoplasmic large DNA viruses (NCLDV, Phylum Nucleocytoviricota newly established by the ICTV in March ), which is related to the family Asfarviridae with the genus Asfivirus (ASFV), but is related to it is still different. In March the ICTV set up the new order Asfuvirales for the closer relatives of the Asfarviridae , with which a taxon is available for the common clade of the Asfaviridae and " Faustoviridae ". Schulz et al (2018) propose a system for this clade as follows:

 Asfuvirales  

 Kaumoebavirus


   

 Asfarviridae ( Asfivirus )


 ? " Faustoviridae " 

 " Pacman Virus "


   

 " Faustovirus "





Template: Klade / Maintenance / Style

In comparison, Guglielmini et al. (2019), Fig. 2, the positions of Asfarviridae and “ Kaumoebavirus ” reversed. The Dinodnavirus was suggested as a possible further member of this extended Asfarviridae group .

Web links

Individual evidence

  1. ↑ a b c d e f g ICTV: ICTV Master Species List 2019.v1 , New MSL including all taxa updates since the 2018b release, March 2020 (MSL # 35)
  2. ↑ a b c Leena H. Bajrai, Samia Benamar, Esam I. Azhar, Catherine Robert, Anthony Levasseur, Didier Raoult, Bernard La Scola; Eric O. Freed (Ed.): Kaumoebavirus, a New Virus That Clusters with Faustoviruses and Asfarviridae. In: Viruses Volume 8, No. 11, October 28, 2016, p. 278, doi: 10.3390 / v8110278 , PMC 5127008 (free full text), PMID 27801826
  3. ↑ a b 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 Communicationsvolume 9, Article number: 4881 (2018) of November 19, 2018, doi: 10.1038 / s41467-018-07335-2
  4. ^ Colson Philippe, La Scola Bernard, Raoult Didier: Giant Viruses of Amoebae: A Journey Through Innovative Research and Paradigm Changes. In: Annual Review of Virology , Volume 4, No. 1, September 29, 2017, pp. 61-85, doi: 10.1146 / annurev-virology-101416-041816 , ISSN  2327-056X
  5. ↑ a b c d e J. Andreani, J. Y. B. Khalil, M. Sevvana, S. Benamar, F. Di Pinto, I. Bitam, P. Colson, T. Klose, M. G. Rossmann, D. Raoult, B. La Scola: Pacmanvirus, a New Giant Icosahedral Virus at the Crossroads between Asfarviridae and Faustoviruses . In: Journal Of Virology , June 26, 2017, 91 (14). pii: e00212-17. Print July 15, 2017. doi: 10.1128 / JVI.00212-17 , PMID 28446673
  6. ↑ Search for Pacman Virus in the ICTV database . Retrieved July 7, 2019.
  7. ↑ D. G. Reteno, S. Benamar, J. Y B. Khalil, J. Andreani, N. Armstrong, T. Klose, M. Rossmann, P. Colson, D. Raoult, B. La Scola: Faustovirus, an asfarvirus-related new lineage of giant viruses infecting amoebae. In: Journal of virology. Volume 89, number 13, July 2015, pp. 6585-6594, doi: 10.1128 / JVI.00115-15 , PMID 25878099 , PMC 4468488 (free full text).
  8. ^ S. Benamar, D. G. Reteno, V. Bandaly, N. Labas, D. Raoult, B. La Scola: Faustoviruses: Comparative Genomics of New Megavirales Family Members. In: Frontiers in microbiology. Volume 7, 2016, p. 3, doi: 10.3389 / fmicb.2016.00003 , PMID 26903952 , PMC 4742530 (free full text).
  9. ↑ T. Klose, D. G. Reteno, S. Benamar, A. Hollerbach, P. Colson, B. La Scola, M. G. Rossmann: Structure of faustovirus, a large dsDNA virus. In: Proceedings of the National Academy of Sciences . Volume 113, number 22, May 2016, pp. 6206-6211, doi: 10.1073 / pnas.1523999113 , PMID 27185929 , PMC 4896704 (free full text).
  10. ↑ Julien Guglielmini, Anthony C. Woo, Mart Krupovic, Patrick Forterre, Morgan Gaia: Diversification of giant and large eukaryotic dsDNnA viruses predated the origin of modern eukaryotes , in: PNAS 116 (39), 10./24. September 2019, pp. 19585-19592, doi: 10.1073 / pnas.1912006116 , PMID 31506349 , Fig. 2
  11. ↑ H. Ogata, K. Toyoda, Y. Tomaru, N. Nakayama, Y. Shirai, J. M. Claverie, K. Nagasaki: Remarkable sequence similarity between the dinoflagellate-infecting marine girus and the terrestrial pathogen African swine fever virus. In: Virol J. , 6, 2009, p. 178.