Kaumoebavirus

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"Kaumoebavirus"
Systematics
Classification : Viruses
Area : Varidnaviria
Empire : Bamfordvirae
Phylum : Nucleocytoviricota
Class : Pokkesviricetes
Order : Asfuvirales
Family : unclassified
Genre : "Kaumoebavirus"
Taxonomic characteristics
Genome : dsDNA circular
Baltimore : Group 1
Cover : icosahedral
Scientific name
"Kaumoebavirus"
Left
NCBI  Taxonomy: 1859492

The proposed giant virus species " Kaumoebavirus " is morphologically and genetically similar to two other proposed taxa of giant viruses, " Faustovirus " and " Pacman virus ", as well as the viruses of the family Asfarviridae with the Asfivirus (ASFV), the causative agent of African swine fever . Kaumoebaviruses have an icosahedral capsid about 250  nm in size, the genome consists of a dsDNA molecule with a length of 350  kbp . It presumably contains 465 genes , the proteins encoded .

The virus was found in 2016 during the cultivation of amoeba of the genus Vermamoeba vermiformis ( Tubulinea ) from a wastewater sample from southern Saudi Arabia . The name is an acronym for English King Abdulaziz University amoeba virus ( King Abdulaziz University -Amöbenvirus).

So far (as of April 2020) the genus " Kaumoebavirus " is not yet registered in the database of the International Committee on Taxonomy of Viruses (ICTV)

construction

As mentioned above, the virus particles (virions) of " Kaumoebavirus " have an icosahedral capsid about 250  nm in size. Its genome is represented by a circular dsDNA molecule containing approximately 351,731 bp. There are no genome repetitive sequences ( English repetitive sequences ) with the exception of a long inverted tandem repeat ( English inverted tandem repeat ) of 1,407 bp in length. The GC content of the genome is 43.7%. According to the bioinformatic data, the genome contains 465 genes that code for proteins that are 113 to 6209 amino acid units in length . No tRNA genes were identified in his genome . As for the homology of the genes, so are

As with " Faustovirus " occurs in " Kaumoebavirus " during the maturation of the mRNA to splice ( English splicing ).

Propagation cycle

At an early stage of the infection (2 hours after entering the host cells of the amoeba Vermamoeba vermiformis ), phagocytosis - vacuoles containing virions (virus particles) of " Kaumoebavirus " are observed in the cytoplasm of the cell. After a further three hours, clusters of 2 to 4 virus particles have already formed in the vacuoles. 4 hours after penetration, viral DNA enters the cytoplasm , and within the next two hours, virus factories can be observed near the cell nucleus , where the viral genome replicates and new virions accumulate; 8 to 16 hours after infection, the newly formed virus particles are detected in the virus factory. During replication, " Kaumoebavirus " does not change the morphology of the cell nucleus. Eventually cell lysis occurs and the virions leak out. The total duration of the reproduction cycle for " Kaumoebavirus " as for " Faustovirus " is 16 to 20 hours.

Systematics

Among the virus proteins, proteins of other viruses of the phylum of the nucleocytoviricota (outdated Nucleocytoviricoa , NCLDV , formerly proposed as the order " Megavirales ") are closest to the " Kaumoebavirus " proteins, in particular this applies to another giant virus, the " Faustovirus ", and the members of the Asfarviridae family . The families Mimiviridae , Phycodnaviridae , Poxviridae , Marseilleviridae , as well as the non-NCLDV family Baculoviridae, are also related to " Kaumoebavirus " . From an evolutionary point of view, “ Kaumoebavirus ” occupies an intermediate position between “ Faustovirus ” and the Asfarviridae .

In 2018 the results of the analysis were published, which further confirmed the close relationship of " Kaumoebavirus " with " Faustovirus " and the Asfarviridae . The study examined whether the sequences encoding the previously identified Asfarviridae - promoters are characteristic, are characteristic also for the huge Kaumoebaviren and Faustoviren. It was previously shown that the representatives of the Asfarviridae are characterized by the presence of A T -rich sequences in promoters. It then turned out that “ Kaumoebavirus ” and “ Faustovirus ” are dominated by AT-rich TATTT and TATATA motifs in promoters, which also brings them closer to the Asfarviridae .

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. In terms of capsid architecture, Faustovirus is closest to Pacman virus .

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 "





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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 .

Individual evidence

  1. ↑ a b c d e f g h ICTV: ICTV Master Species List 2019.v1 , New MSL including all taxa updates since the 2018b release, March 2020 (MSL # 35)
  2. ↑ NCBI: Kaumoebavirus (species)
  3. ↑ a b c d e f 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
  4. ↑ Oliveira G. P., de Aquino I. L. M., Luiz A. P. M. F., Abrahão J. S .: Putative Promoter Motif Analyzes Reinforce the Evolutionary Relationships Among Faustoviruses, Kaumoebavirus, and Asfarvirus . In: Frontiers In Microbiology Volume 9 of May 23, 2018, p. 1041, eCollection 2018, doi: 10.3389 / fmicb.2018.01041 , PMID 29875752
  5. ↑ Andreani J., Khalil JYB, Sevvana M., Benamar S., Di Pinto F., Bitam I., Colson P., Klose T., Rossmann MG, Raoult D., La Scola B .: 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. ↑ DG Reteno, p Benamar, JB Khalil, J. Andreani, N. Armstrong, T. Klose, M. Ross, P. Colson, D. Raoult, B. La Scola: Faustovirus to 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).
  7. ↑ S. Benamar, DG Reteno, V. Bandaly, N. Labas, D. Raoult, B. La Scola: Faustoviruses: Comparative Genomics of New Mega Viral Family Members. In: Frontiers in microbiology. Volume 7, 2016, p. 3, doi : 10.3389 / fmicb.2016.00003 , PMID 26903952 , PMC 4742530 (free full text).
  8. ↑ T. Klose, DG Reteno, S. Benamar, A. Hollerbach, P. Colson, B. La Scola, MG 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).
  9. ↑ 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 ) from November 19, 2018, doi: 10.1038 / s41467-018-07335-2
  10. ^ Pierre-Philippe Dechant: Recent developments in mathematical virology . (PDF) ICERM, York St. John University, November 15, 2018
  11. ↑ 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
  12. ↑ 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.

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