Orpheovirus
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" Orpheovirus " is a proposed genus of giant viruses from the Phylum Nucleocytoviricota (outdated English Nucleocytoplasmic large DNA viruses , NCLDV ).
Like all these giant viruses, orpheoviruses have a genome made up of double-stranded DNA (dsDNA). The first description of the genus was published in early 2018 by J. Andrean et al. released. They were able to isolate the virus ( species “ Orpheovirus IHUMI-LCC ”) from samples of rat faeces using amoeba of the species Vermamoeba vermiformis ( Tubulinea : Euamoebida / Tubulinida ). The first and so far (as of July 2019) only species of the genus is " Orpheovirus IHUMI-LCC2 ".
As of July 2019, neither the genus " Orpheovirus " nor this species are registered by the International Committee on Taxonomy of Viruses (ICTV) (Master Species List # 34 2018b).
The name is apparently derived from Orpheus , singer and poet in Greek mythology .
construction
The virus particles (virions) are (ovoidaler) of ovoid shape and have at least one thick membrane having an opening ( ostiole ) at the tip ( apex ), similar to pandoravirus . In these, however, the envelope ( tegument ) consists of three layers, each about 20 to 25 nm. The virus particles showed a dark, dense outer layer, sparsely covered with short fibrils . Underneath this there is an intermediate space of medium density, which is delimited inward by a very dense membrane ( English hyperdense membrane ). The length of the virions ranges from 900 to 1,100 nm , some virions could even be up to 1,300 nm long. Their diameter is around 500 nm.
" Orpheovirus IHUMI-LCC2 " has a circular genome of 1,473,573 base pairs with a GC content of 25%. The genome has different areas with repetitive sequences ( english repeats ): 57 palindromic sequences, and very high in comparison with other giant viruses number of 1,527 tandem repeats and 832 candidates for inverted sequences ( English inverted sequences ). At least 57.5% of the genes of " Orpheovirus " are open reading frames ( English open reading frames , ORFs). Of 509 encoded proteins , 148 cases (12.3%) had the best match with genes from other viruses, 176 cases with eukaryotic genes (14.7%) and in 183 cases (15.3%) with prokaryotic genes (from bacteria or archaea ). Among the viruses, there was best agreement with “ Pithovirus sibericum ”, “ P. massiliensis ”, “ Cedratvirus ” (proposed family “ Pithoviridae ”), as well as Mimivirus and toilet viruses (family Mimiviridae ). No genes for tRNA (transfer RNA) were found.
Interestingly, gene homologs have been found with the Sputnik virophage and the Zamilon virophage , both genus Sputnik virus .
Propagation cycle
The entry of the virions into the host happens through phagocytosis , whereby the virions manage to escape the phagosomal process (digestion process) that normally follows . The virus DNA is then released into the cytoplasm through the ostiol-like tip . The virus factories typical of giant viruses are easy to recognize 14 to 16 hours after infection. At this early stage of virus synthesis, the picture is similar to that of “ Pithovirus ” and “ Cedratvirus ”. The host cells are then densely filled with new virions 20 hours after infection. The virions appear (by cell outbreaks english bursts ) or exocytosis emerge and are then detectable outside the amoeba cell. After a further 4 to 18 hours, complete cell eruption occurs. This relatively slow reproduction cycle is typical for the host Vermamoeba vermiformis used in the laboratory and was also observed when this species was infected with other viruses, unlike when these infected amoebas of the genus Acanthamoeba , for example with " Faustovirus " or " Pacman virus ". So it could be that " orpheovirus " reproduces faster in its natural host.
Systematics
The phylogenetic analysis of the genome of " Orpheovirus " shows a relationship with the proposed family " Pithoviridae ". However, some specific features of the genome testify to a different development of the orpheovirus IHUMI-LCC2 compared to " Cedratvirus " or " Pithovirus " (both putative Pithoviridae ). The authors of the first publication (Andreani et al. , 2018) therefore suggested setting up a separate family “ Orpheoviridae ” for “ Orpheovirus ” , closely related to the “ Pithoviridae ” that were also only proposed so far .
Meanwhile, Andreani et al. (2018) found that a candidate from metagenomic analyzes assigned to the Rickettsiales bacteria is apparently a giant virus closely related to the orpheovirus ( misidentified virus ) - a mix-up that also happened at the beginning of the story of the discovery of the mimivirus . In addition, the authors found evidence of a second virus ( mine drainage ) that is basically in the extended family of the " Pithoviridae " (ie the group of the " Pithoviridae " plus " Orpheoviridae ").
For the family of " Pithoviridae " extended by these finds , Schulz et al. the following system within the NCLDV (supplemented by these additional finds from Andreani et al. ):
| " Pithovirus-like viruses " (" Pithoviridae " sl ) |
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Individual evidence
- ↑ a b c d e ICTV: ICTV Master Species List 2019.v1 , New MSL including all taxa updates since the 2018b release, March 2020 (MSL # 35)
- ↑ a b c d e f g 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
- ↑ NCBI: Orpheovirus IHUMI-LCC2 (species)
- ↑ a b c d Julien Andreani, Jonathan Verneau, Didier Raoult, Anthony Levasseurn Bernard La Scola: Deciphering viral presences: two novel partial giant viruses detected in marine metagenome and in a mine drainage metagenome , in: Virology Journal, Volume 15, No. 66, April 10, 2018, doi: 10.1186 / s12985-018-0976-9
- ↑ Search Cedratvirus database in ICTV . Retrieved July 6, 2019.
- ↑ Reteno DG, Benamar S, Khalil JB, Andreani J, Armstrong N, Klose T, Rossmann M, Colson P, Raoult D, La Scola B: Faustovirus, an asfarvirus-related new lineage of giant viruses infecting amoebae , in: J Virol . July 2015; 89 (13), pp. 6585-94, PMID 25878099 , PMC 4468488 (free full text), doi: 10.1128 / JVI.00115-15
- ↑ Julien Andreani, Jacques Yaacoub Bou Khalil, Madhumati Sevvana, Samia Benamar, Fabrizio Di Pinto, Idir Bitam, Philippe Colson, Thomas Klose, Michael G. Rossmann, Didier Raoult; Bernard La Scola: Pacman virus, a New Giant Icosahedral Virus at the Crossroads between Asfarviridae and Faustoviruses , in: J Virolv. 91 (14); July 15, 2017, PMID 28446673 , PMC 5487549 (free full text)
- ↑ Center national de la recherche scientifique: List of the main “giant” viruses known as of today , Université Aix Marseille, April 18, 2018
- ↑ 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
- ↑ Jan Osterkamp: Virology: Giant viruses are more widespread than expected , on: Spektrum.de from November 20, 2018.
- ↑ 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
- ↑ 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
- ↑ a b 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: Frontiers in Microbiology . tape 8 , January 22, 2018, ISSN 1664-302X , doi : 10.3389 / fmicb.2017.02643 .
Web links
- Graziel Oliveira, Bernard La Scola, Jônatas Abrahão: Giant virus vs amoeba: fight for supremacy , in: Virol J 16, 126, November 4, 2019, doi: 10.1186 / s12985-019-1244-3 , PDF