Tupanvirus: Difference between revisions
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'''Tupanvirus''' is a relatively new [[genus]] of [[virus]] that was introduced into the virosphere in 2018.<ref name=":02">{{Cite journal|last=Abrahão|first=Jônatas|last2=Silva|first2=Lorena|last3=Silva|first3=Ludmila Santos|last4=Khalil|first4=Jacques Yaacoub Bou|last5=Rodrigues|first5=Rodrigo|last6=Arantes|first6=Thalita|last7=Assis|first7=Felipe|last8=Boratto|first8=Paulo|last9=Andrade|first9=Miguel|last10=Kroon|first10=Erna Geessien|last11=Ribeiro|first11=Bergmann|date=2018-12|title=Tailed giant Tupanvirus possesses the most complete translational apparatus of the known virosphere|url=http://www.nature.com/articles/s41467-018-03168-1|journal=Nature Communications|language=en|volume=9|issue=1|pages=749|doi=10.1038/s41467-018-03168-1|issn=2041-1723|pmc=PMC5829246|pmid=29487281}}</ref> The genus is composed of two species of virus that are in the [[giant virus]] group. Researchers discovered the first isolate in 2012 from deep water sediment samples taken at 3000m depth off the coast of [[Brazil]].<ref name=":02" /> The second isolate was collected from a [[soda lake]] in Southern Nhecolândia, Brazil in 2014.<ref name=":02" /> They are named after Tupã (Tupan), a Guaraní thunder god, and the places they were found. These are the first viruses reported to possess genes for amino-acyl tRNA synthetases for all 20 standard [[Amino acid|amino acids]].<ref name=":02" /><ref name=":12">{{Cite web|date=2018-02-27|title=These giant viruses have more protein-making gear than any known virus|url=https://www.sciencenews.org/article/these-giant-viruses-have-more-protein-making-gear-any-known-virus|access-date=2021-04-07|website=Science News|language=en-US}}</ref><ref>{{Cite book|last=F|first=Schulz,|url=http://worldcat.org/oclc/1114659455|title=Giant viruses with an expanded complement of translation system components|date=2017-04-07|publisher=eScholarship, University of California|oclc=1114659455}}</ref> The discovery of these new strains of giant virus adds considerable information to the literature surrounding the virosphere and calls into question how we classify viruses. {{Virusbox/sandbox |
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{{short description|Proposed genus of viruses}} |
{{short description|Proposed genus of viruses}} |
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{{Distinguish|Tupavirus}} |
{{Distinguish|Tupavirus}} |
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== Classification == |
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'''Tupanvirus''' is the name of two [[giant virus]]es, Tupanvirus deep ocean and Tupanvirus soda lake. They are named after [[Tupã (mythology)|Tupã]] (Tupan), a [[Guaraní people|Guaraní]] thunder god, and the places they were found. These are the first viruses reported to possess genes for amino-acyl tRNA synthetases for all 20 standard amino acids.<ref name='Sci mag'>{{cite web|url=https://www.sciencenews.org/article/these-giant-viruses-have-more-protein-making-gear-any-known-virus?tgt=nr|title=These giant viruses have more protein-making gear than any known virus|first=Dan|last=Garisto|date=27 February 2018|publisher=}}</ref><ref name='Nature Comm'>{{cite journal|title=Tailed giant Tupanvirus possesses the most complete translational apparatus of the known virosphere| first1=Jônatas| last1=Abrahão|first2=Lorena|last2=Silva|first3=Ludmila Santos|last3=Silva|first4=Jacques Yaacoub Bou| last4=Khalil| first5=Rodrigo| last5=Rodrigues|first6=Thalita|last6=Arantes|first7=Felipe|last7=Assis|first8=Paulo|last8=Boratto|first9=Miguel|last9=Andrade|first10=Erna Geessien|last10=Kroon|first11=Bergmann|last11=Ribeiro|first12=Ivan|last12=Bergier|first13=Herve|last13=Seligmann|first14=Eric|last14=Ghigo|first15=Philippe|last15=Colson|first16=Anthony|last16=Levasseur|first17=Guido|last17=Kroemer|first18=Didier|last18=Raoult|first19=Bernard La|last19=Scola|date=27 February 2018| journal=Nature Communications| volume=9|issue=1| pages=749|doi=10.1038/s41467-018-03168-1|pmid = 29487281| pmc=5829246| bibcode=2018NatCo...9..749A}}</ref><ref>{{cite journal|title=Giant viruses with an expanded complement of translation system components| first1=Frederik|last1=Schulz|first2=Natalya|last2=Yutin|first3=Natalia N.|last3=Ivanova|first4=Davi R.|last4=Ortega|first5=Tae Kwon|last5=Lee|first6=Julia|last6=Vierheilig|first7=Holger|last7=Daims|first8=Matthias|last8=Horn|first9=Michael|last9=Wagner|first10=Grant J.|last10=Jensen|first11=Nikos C.|last11=Kyrpides|first12=Eugene V.|last12=Koonin|first13=Tanja|last13=Woyke| date=7 April 2017| journal=Science| volume=356|issue=6333|pages=82–85| doi=10.1126/science.aal4657|pmid=28386012|bibcode = 2017Sci...356...82S|url=https://cloudfront.escholarship.org/dist/prd/content/qt0kf9t6gn/qt0kf9t6gn.pdf}}</ref> |
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The genus Tupanvirus was first described in 2018 with the discovery of the two isolates of tupanviruses found in soda lake and deep oceanic sediments samples collected in Brazil.<ref name=":02" /> The genus is currently unassigned but hypothesized to be a member of the family [[Mimiviridae]], along with the other amoeba-infecting viruses.<ref name=":2" /> Members of the family Mimiviridae includes the type species [[Acanthamoeba polyphaga mimivirus]] (APMV) that is known for its large size of ~500 nm in diameter.<ref name=":2">{{Cite journal|last=Rodrigues|first=Rodrigo Araújo Lima|last2=Mougari|first2=Said|last3=Colson|first3=Phillipe|last4=La Scola|first4=Bernard|last5=Abrahão|first5=Jônatas Santos|date=2018-10-05|title=“Tupanvirus”, a new genus in the family Mimiviridae|url=http://dx.doi.org/10.1007/s00705-018-4067-4|journal=Archives of Virology|volume=164|issue=1|pages=325–331|doi=10.1007/s00705-018-4067-4|issn=0304-8608}}</ref> In contrast, the typical virus size range is approximately 20-200 nm.<ref>{{Cite journal|last=Fuhrman|first=Jed A.|date=1999-06-XX|title=Marine viruses and their biogeochemical and ecological effects|url=https://www.nature.com/articles/21119|journal=Nature|language=en|volume=399|issue=6736|pages=541–548|doi=10.1038/21119|issn=1476-4687}}</ref> Mimiviruses also possess [[fibril]] structures on the capsid as well as genes encoding proteins for nucleotide synthesis and various metabolisms that are not found in other viruses.<ref>{{Cite journal|last=Colson|first=Philippe|last2=La Scola|first2=Bernard|last3=Levasseur|first3=Anthony|last4=Caetano-Anollés|first4=Gustavo|last5=Raoult|first5=Didier|date=2017-04|title=Mimivirus: leading the way in the discovery of giant viruses of amoebae|url=https://www.nature.com/articles/nrmicro.2016.197|journal=Nature Reviews Microbiology|language=en|volume=15|issue=4|pages=243–254|doi=10.1038/nrmicro.2016.197|issn=1740-1534|pmc=PMC7096837|pmid=28239153}}</ref> |
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Tupanvirus measure up to 1.2 μm in complete virion length, with a [[capsid]] similar to that of amoebal mimiviruses in size (~450 nm) and structure. However, the Tupanvirus virion presents a large cylindrical tail (~550 nm × 450 nm diameter) attached to the base of the capsid.<ref name='Nature Comm'/> Some particles can reach up to 2.3 μm because of the variation in tail size. |
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Unlike the other mimiviruses in the Mimiviridae, tupanvirus has a ~550 nm long cylindrical tail covered with fibrils that is attached to the base of the [[capsid]].<ref name=":2" /> This morphological feature makes tupanvirus the largest described virus (approximately ~ 1.2 μm in length with the tail) with the longest tail ever observed a in virus.<ref name=":02" /><ref name=":2" /> Tupanviruses are also capable of infecting a wider range of amoebae than other mimiviruses, and produce a [[Cytotoxicity|cytotoxic]] effect in host and non-host organisms that is not observed in APMV.<ref name=":2" /> In addition, phylogenomic results revealed that the genus Tupanvirus is separate from the other viruses in the family Mimiviridae.<ref name=":2" /> |
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== Morphology == |
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The morphology of Tupanvirus can be similarly compared to that of other ‘amoeba-infecting mimiviruses’.<ref name=":2" /> This is because of similarities between the capsid of Tupanvirus and that of other amoebae-infecting mimiviruses.<ref name=":02" /> The capsid of Tupanvirus measures approximately 450nm.<ref name=":2" /> One major difference is that the Tupanvirus virion presents a large cylindrical tail (~550 nm × 450 nm diameter) attached to the base of the capsid.<ref name=":02" /> Both the capsid and cylindrical tail are covered in fibrils.<ref name=":2" /> Tupanvirus can measure up to 1.2 um in length, and some particles can reach up to 2.3 μm because of the “high degree of plasticity in the size of the tail”.<ref name=":02" /><ref name=":2" /> Also to note is a lipid membrane is seen within the capsid. Additionally, their capsid is described as having a ‘stargate structure’.<ref name=":2" /> This star-shaped vertex is present in other mimivurises, and acts as a seal for the apex of the capsid.<ref>{{Cite journal|last=Pires de Souza|first=Gabriel Augusto|last2=Rolland|first2=Clara|last3=Nafeh|first3=Bariaa|last4=La Scola|first4=Bernard|last5=Colson|first5=Philippe|date=2021-02-10|title=Giant virus-related sequences in the 5300-year-old Ötzi mummy metagenome|url=http://dx.doi.org/10.1007/s11262-021-01823-2|journal=Virus Genes|volume=57|issue=2|pages=222–227|doi=10.1007/s11262-021-01823-2|issn=0920-8569}}</ref> It has also been stated that the tail of Tupanvirus is less electron dense than the capsid.<ref name=":2" /> |
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== Genome == |
== Genome == |
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The genome contains roughly 1.5 million [[Base pair|base pairs]] of double-stranded [[DNA]], coding for 1276–1425 predicted proteins, making it the fourth largest among viral genomes.<ref name=":1">{{Cite web|date=2018-02-27|title=These giant viruses have more protein-making gear than any known virus|url=https://www.sciencenews.org/article/these-giant-viruses-have-more-protein-making-gear-any-known-virus|access-date=2021-04-07|website=Science News|language=en-US}}</ref> While 30% of the genes are new and not found in other viruses, genomic analysis shows most of the known genes can be related to amoeba-infecting mimiviruses, with the rest corresponding to eukaryotes and bacteria. The shared genes of tupanvirus with different lineages of amoeba-infecting mimiviruses indicate it as a separate genus within family Mimiviridae.<ref name=":02" /> For example, its A/T rich genome resembles that of other amoebal mimiviruses and suggests a preference for codons formed by A/T-rich sequences. As well, the frequent occurrence of the “AAAATTGA” promoter motif is also similar to that of other mimiviruses.<ref name=":02" /><ref name=":3">{{Citation|last=Rodrigues|first=Rodrigo Araújo Lima|title=Chapter Four - The Complex Nature of Tupanviruses|date=2019-01-01|url=https://www.sciencedirect.com/science/article/pii/S0065352718300447|work=Advances in Virus Research|volume=103|pages=135–166|editor-last=Kielian|editor-first=Margaret|publisher=Academic Press|language=en|access-date=2021-04-07|last2=Arantes|first2=Thalita Souza|last3=Oliveira|first3=Graziele Pereira|last4=dos Santos Silva|first4=Ludmila Karen|last5=Abrahão|first5=Jônatas Santos|editor2-last=Mettenleiter|editor2-first=Thomas C.|editor3-last=Roossinck|editor3-first=Marilyn J.}}</ref> |
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The genome contains roughly 1.5 million [[base pair]]s of double-stranded [[DNA]],<ref name="Sci mag" /> coding for 1276–1425 predicted proteins. Many genes that encode for processes found in cellular organisms are found in Tupanvirus genome.<ref name="Nature Comm" /> As a giant virus, Tupanvirus present the largest [[translational apparatus]] within the known virosphere. The analysis of tupanviruses constitutes a new step towards understanding the evolution of giant viruses. |
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As a giant virus, tupanvirus presents the largest [[translational apparatus]] within the known virosphere, carrying 20 aminoacyl tRNA synthetase (aaRS) and 70 transfer RNAs (tRNA), while the rest are involved in RNA maturation and splicing, as well as ribosomal protein modification.<ref name=":02" /> Moreover, tupanviruses contain a number of DNA-independent RNA synthesizing polymerases and enzymes as well as transcription factors that are involved in viral transcription.<ref name=":3" /> Furthermore, many genes that encode for processes found in cellular organisms are also found in the Tupanvirus genome, which contains a richer gene set than some bacteria and archaea, and even some eukaryotes.<ref name=":02" /> As a result, the analysis of tupanviruses constitutes a new step towards understanding the evolution of giant viruses, because such diverse and complete gene sets not only surpass that of other viral genomes, but also rival that of bacteria and even eukaryotes. In fact, tupanvirus is the only known virus to host all 20 aaRS, exceeding other giant viruses like [[Klosneuvirus]]; yet, there is no agreement on whether these genes are host-derived or passed down from an ancestral mimivirus.<ref name=":2" /> One such extraordinary example are two copies of an 18 S rRNA intronic region that are highly expressed during viral replication. Although these intronic regions also exist in other mimiviruses, the tupanvirus 18S rRNA is phylogenetically different with their function still unknown.<ref name=":02" /> |
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<gallery widths="300" heights="200">File:Tupanvirus-Translational-Factors.png|Tupanvirus genome translational factors |
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</gallery> |
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== Host == |
== Host == |
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Tupanviruses have the ability to infect a wider range of hosts than other giant viruses, including many [[amoeba]]<nowiki/>e of the genus [[Acanthamoeba|Acanthameoba]] (as well as members of the species Vermamoeba vermiformis, [[Dictyostelium discoideum]] and Willartia magna),<ref name=":2" /> and may also infect other [[Protist|protists]]. There are no documented threats to humans.<ref name=":1" /> The tupanvirus’ [[Generalist and specialist species|generalist]] approach may be attributed to the low species richness and abundance of the virus’ habitat.<ref>{{Cite journal|last=Sergeev|first=V. N.|last2=Gerasimenko|first2=L. M.|last3=Zavarzin|first3=G. A.|date=2002-11-01|title=The Proterozoic History and Present State of Cyanobacteria|url=https://doi.org/10.1023/A:1021415503436|journal=Microbiology|language=en|volume=71|issue=6|pages=623–637|doi=10.1023/A:1021415503436|issn=1608-3237}}</ref> |
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Tupanviruses are able to infect [[protist]]s and [[amoeba]]s, but probably pose no threat to humans.<ref name="Sci mag" /> |
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Tupanvirus-infected amoebas also present a new virus-host interaction not previously observed among other amoebae. Infected cells were found to aggregate with non-infected cells, a mechanism suggested to be mediated by [[Mannan-binding lectin|mannose binding protein]] gene expression (MBP)<ref name=":4" />. The clusters of affected cells were shown to increase viral dissemination within the host, thus increasing virulence of the virus.<ref name=":4">{{Cite journal|last=Oliveira|first=Graziele|last2=Silva|first2=Lorena|last3=Leão|first3=Thiago|last4=Mougari|first4=Said|last5=da Fonseca|first5=Flávio Guimarães|last6=Kroon|first6=Erna Geessien|last7=La Scola|first7=Bernard|last8=Abrahão|first8=Jônatas Santos|date=2019-01-17|title=Tupanvirus-infected amoebas are induced to aggregate with uninfected cells promoting viral dissemination|url=https://www.nature.com/articles/s41598-018-36552-4|journal=Scientific Reports|language=en|volume=9|issue=1|pages=183|doi=10.1038/s41598-018-36552-4|issn=2045-2322}}</ref> The generalist approach, in conjunction with aggregation behaviour, decreases the dilution effect and increases host-encounter rates. |
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<gallery widths="300" heights="200"> |
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{{Portal|Viruses}} |
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File:Amoebal-Clustering-Tupanvirus.jpeg|Tupanvirus-induced clustering (as seen in ''A. castellani'') |
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{{Baltimore classification}} |
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</gallery> |
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{{Taxonbar|from=Q50323864}} |
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== Life Cycle and Host Interaction == |
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[[Category:Nucleocytoplasmic large DNA viruses]] |
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[[Category:Unaccepted virus taxa]] |
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[[Category:Mimiviridae]] |
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===== '''Attachment''' ===== |
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{{virus-stub}} |
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Viral particles attach directly to the host cell surface<ref name=":4" />. The attachment process occurs very rapidly. Virions can be visibly attached at 0 hours past infection. Specific mechanism still unknown.<ref name=":4" /> |
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===== '''Entry''' ===== |
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Virions enter via [[phagocytosis]]<ref name=":5" />. Generally only one particle will be present in each [[phagosome]], although several particles may enter the intracellular matrix in different phagosomes at the same time.<ref name=":5">{{Cite journal|last=Silva|first=Lorena C. F.|last2=Rodrigues|first2=Rodrigo Araújo Lima|last3=Oliveira|first3=Graziele Pereira|last4=Dornas|first4=Fabio Pio|last5=La Scola|first5=Bernard|last6=Kroon|first6=Erna G.|last7=Abrahão|first7=Jônatas S.|date=2019|title=Microscopic Analysis of the Tupanvirus Cycle in Vermamoeba vermiformis|url=https://www.frontiersin.org/articles/10.3389/fmicb.2019.00671/full|journal=Frontiers in Microbiology|language=English|volume=10|doi=10.3389/fmicb.2019.00671|issn=1664-302X}}</ref> This Tupanvirus uses [[Lipid bilayer fusion|membrane fusion]] in order to release its genome. The viral capsid contains a lipid membrane that facilitates fusion with the phagosome membrane to release the viral genome. The virus also releases the contents kept in the tail after an invagination of the phagosome between the two tail components results in fusion.<ref name=":02" /> |
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===== '''Replication''' ===== |
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The viral genome is released from the phagosome into the amoeba’s [[cytoplasm]].<ref name=":02" /> This virus facilitates aggregation of amoeba hosts in order to replicate rapidly and have a supply of hosts for progeny particles.<ref name=":4" /> Bunch formation happens rapidly after infection and will continue as long as host cells are living. Bunches can re-form after mechanical separation as long as host cells are living.<ref name=":4" /> Replication factories are formed as early as 8 h.p.i. up to 12 h.p.i..<ref name=":4" /><ref name=":5" /> |
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===== '''Assembly''' ===== |
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Initially, when replication factories are still immature, new virions are assembled as soon as possible.<ref name=":5" /> Therefore, many particles at various stages of assembly may be present inside a single factory. Once the factory has matured capsid assembly is finished and the genome is incorporated. The tails are attached to the capsid following genome incorporation.<ref name=":5" /> Assembly of particles happens on a loose timeline, resulting in particles at varying stages of assembly at the time of release. |
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===== '''Release''' ===== |
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Viral particles are released, facilitated by cell [[lysis]].<ref name=":5" /> When infecting the amoeba in the species ''Vermamoeba vermiformis'' many assembled particles are not functional at the time of release. As many as half of released particles are not infectious; this phenomenon is also present when infecting host amoeba ''Acanthamoeba castellanii''.<ref name=":5" /> Although more research is required it is hypothesized that the production of non-infectious particles may be a normal part of the replication cycle.<ref name=":5" /> |
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Due to its recent discovery, there is still little information on tupanvirus in the [[Scientific literature|literature]], and more research is needed to understand the replication and life cycle of this virus and its interaction with hosts. |
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Revision as of 04:19, 23 April 2021
Tupanvirus is a relatively new genus of virus that was introduced into the virosphere in 2018.[1] The genus is composed of two species of virus that are in the giant virus group. Researchers discovered the first isolate in 2012 from deep water sediment samples taken at 3000m depth off the coast of Brazil.[1] The second isolate was collected from a soda lake in Southern Nhecolândia, Brazil in 2014.[1] They are named after Tupã (Tupan), a Guaraní thunder god, and the places they were found. These are the first viruses reported to possess genes for amino-acyl tRNA synthetases for all 20 standard amino acids.[1][2][3] The discovery of these new strains of giant virus adds considerable information to the literature surrounding the virosphere and calls into question how we classify viruses. {{Virusbox/sandbox
| Tupanvirus | |
|---|---|
| |
Virus classification 
| |
| (unranked): | Virus |
| Realm: | Varidnaviria |
| Kingdom: | Bamfordvirae |
| Phylum: | Nucleocytoviricota |
| Class: | Megaviricetes |
| Order: | Imitervirales |
| Family: | Mimiviridae (?) |
| Genus: | Tupanvirus |
| Species | |
Classification
The genus Tupanvirus was first described in 2018 with the discovery of the two isolates of tupanviruses found in soda lake and deep oceanic sediments samples collected in Brazil.[1] The genus is currently unassigned but hypothesized to be a member of the family Mimiviridae, along with the other amoeba-infecting viruses.[4] Members of the family Mimiviridae includes the type species Acanthamoeba polyphaga mimivirus (APMV) that is known for its large size of ~500 nm in diameter.[4] In contrast, the typical virus size range is approximately 20-200 nm.[5] Mimiviruses also possess fibril structures on the capsid as well as genes encoding proteins for nucleotide synthesis and various metabolisms that are not found in other viruses.[6]
Unlike the other mimiviruses in the Mimiviridae, tupanvirus has a ~550 nm long cylindrical tail covered with fibrils that is attached to the base of the capsid.[4] This morphological feature makes tupanvirus the largest described virus (approximately ~ 1.2 μm in length with the tail) with the longest tail ever observed a in virus.[1][4] Tupanviruses are also capable of infecting a wider range of amoebae than other mimiviruses, and produce a cytotoxic effect in host and non-host organisms that is not observed in APMV.[4] In addition, phylogenomic results revealed that the genus Tupanvirus is separate from the other viruses in the family Mimiviridae.[4]
Morphology
The morphology of Tupanvirus can be similarly compared to that of other ‘amoeba-infecting mimiviruses’.[4] This is because of similarities between the capsid of Tupanvirus and that of other amoebae-infecting mimiviruses.[1] The capsid of Tupanvirus measures approximately 450nm.[4] One major difference is that the Tupanvirus virion presents a large cylindrical tail (~550 nm × 450 nm diameter) attached to the base of the capsid.[1] Both the capsid and cylindrical tail are covered in fibrils.[4] Tupanvirus can measure up to 1.2 um in length, and some particles can reach up to 2.3 μm because of the “high degree of plasticity in the size of the tail”.[1][4] Also to note is a lipid membrane is seen within the capsid. Additionally, their capsid is described as having a ‘stargate structure’.[4] This star-shaped vertex is present in other mimivurises, and acts as a seal for the apex of the capsid.[7] It has also been stated that the tail of Tupanvirus is less electron dense than the capsid.[4]
Genome
The genome contains roughly 1.5 million base pairs of double-stranded DNA, coding for 1276–1425 predicted proteins, making it the fourth largest among viral genomes.[8] While 30% of the genes are new and not found in other viruses, genomic analysis shows most of the known genes can be related to amoeba-infecting mimiviruses, with the rest corresponding to eukaryotes and bacteria. The shared genes of tupanvirus with different lineages of amoeba-infecting mimiviruses indicate it as a separate genus within family Mimiviridae.[1] For example, its A/T rich genome resembles that of other amoebal mimiviruses and suggests a preference for codons formed by A/T-rich sequences. As well, the frequent occurrence of the “AAAATTGA” promoter motif is also similar to that of other mimiviruses.[1][9]
As a giant virus, tupanvirus presents the largest translational apparatus within the known virosphere, carrying 20 aminoacyl tRNA synthetase (aaRS) and 70 transfer RNAs (tRNA), while the rest are involved in RNA maturation and splicing, as well as ribosomal protein modification.[1] Moreover, tupanviruses contain a number of DNA-independent RNA synthesizing polymerases and enzymes as well as transcription factors that are involved in viral transcription.[9] Furthermore, many genes that encode for processes found in cellular organisms are also found in the Tupanvirus genome, which contains a richer gene set than some bacteria and archaea, and even some eukaryotes.[1] As a result, the analysis of tupanviruses constitutes a new step towards understanding the evolution of giant viruses, because such diverse and complete gene sets not only surpass that of other viral genomes, but also rival that of bacteria and even eukaryotes. In fact, tupanvirus is the only known virus to host all 20 aaRS, exceeding other giant viruses like Klosneuvirus; yet, there is no agreement on whether these genes are host-derived or passed down from an ancestral mimivirus.[4] One such extraordinary example are two copies of an 18 S rRNA intronic region that are highly expressed during viral replication. Although these intronic regions also exist in other mimiviruses, the tupanvirus 18S rRNA is phylogenetically different with their function still unknown.[1]
-
Tupanvirus genome translational factors
Host
Tupanviruses have the ability to infect a wider range of hosts than other giant viruses, including many amoebae of the genus Acanthameoba (as well as members of the species Vermamoeba vermiformis, Dictyostelium discoideum and Willartia magna),[4] and may also infect other protists. There are no documented threats to humans.[8] The tupanvirus’ generalist approach may be attributed to the low species richness and abundance of the virus’ habitat.[10]
Tupanvirus-infected amoebas also present a new virus-host interaction not previously observed among other amoebae. Infected cells were found to aggregate with non-infected cells, a mechanism suggested to be mediated by mannose binding protein gene expression (MBP)[11]. The clusters of affected cells were shown to increase viral dissemination within the host, thus increasing virulence of the virus.[11] The generalist approach, in conjunction with aggregation behaviour, decreases the dilution effect and increases host-encounter rates.
-
Tupanvirus-induced clustering (as seen in A. castellani)
Life Cycle and Host Interaction
Attachment
Viral particles attach directly to the host cell surface[11]. The attachment process occurs very rapidly. Virions can be visibly attached at 0 hours past infection. Specific mechanism still unknown.[11]
Entry
Virions enter via phagocytosis[12]. Generally only one particle will be present in each phagosome, although several particles may enter the intracellular matrix in different phagosomes at the same time.[12] This Tupanvirus uses membrane fusion in order to release its genome. The viral capsid contains a lipid membrane that facilitates fusion with the phagosome membrane to release the viral genome. The virus also releases the contents kept in the tail after an invagination of the phagosome between the two tail components results in fusion.[1]
Replication
The viral genome is released from the phagosome into the amoeba’s cytoplasm.[1] This virus facilitates aggregation of amoeba hosts in order to replicate rapidly and have a supply of hosts for progeny particles.[11] Bunch formation happens rapidly after infection and will continue as long as host cells are living. Bunches can re-form after mechanical separation as long as host cells are living.[11] Replication factories are formed as early as 8 h.p.i. up to 12 h.p.i..[11][12]
Assembly
Initially, when replication factories are still immature, new virions are assembled as soon as possible.[12] Therefore, many particles at various stages of assembly may be present inside a single factory. Once the factory has matured capsid assembly is finished and the genome is incorporated. The tails are attached to the capsid following genome incorporation.[12] Assembly of particles happens on a loose timeline, resulting in particles at varying stages of assembly at the time of release.
Release
Viral particles are released, facilitated by cell lysis.[12] When infecting the amoeba in the species Vermamoeba vermiformis many assembled particles are not functional at the time of release. As many as half of released particles are not infectious; this phenomenon is also present when infecting host amoeba Acanthamoeba castellanii.[12] Although more research is required it is hypothesized that the production of non-infectious particles may be a normal part of the replication cycle.[12]
Due to its recent discovery, there is still little information on tupanvirus in the literature, and more research is needed to understand the replication and life cycle of this virus and its interaction with hosts.
References
- ^ a b c d e f g h i j k l m n o p Abrahão, Jônatas; Silva, Lorena; Silva, Ludmila Santos; Khalil, Jacques Yaacoub Bou; Rodrigues, Rodrigo; Arantes, Thalita; Assis, Felipe; Boratto, Paulo; Andrade, Miguel; Kroon, Erna Geessien; Ribeiro, Bergmann (2018-12). "Tailed giant Tupanvirus possesses the most complete translational apparatus of the known virosphere". Nature Communications. 9 (1): 749. doi:10.1038/s41467-018-03168-1. ISSN 2041-1723. PMC 5829246. PMID 29487281.
{{cite journal}}: Check date values in:|date=(help)CS1 maint: PMC format (link) - ^ "These giant viruses have more protein-making gear than any known virus". Science News. 2018-02-27. Retrieved 2021-04-07.
- ^ F, Schulz, (2017-04-07). Giant viruses with an expanded complement of translation system components. eScholarship, University of California. OCLC 1114659455.
{{cite book}}: CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link) - ^ a b c d e f g h i j k l m n Rodrigues, Rodrigo Araújo Lima; Mougari, Said; Colson, Phillipe; La Scola, Bernard; Abrahão, Jônatas Santos (2018-10-05). ""Tupanvirus", a new genus in the family Mimiviridae". Archives of Virology. 164 (1): 325–331. doi:10.1007/s00705-018-4067-4. ISSN 0304-8608.
- ^ Fuhrman, Jed A. (1999-06-XX). "Marine viruses and their biogeochemical and ecological effects". Nature. 399 (6736): 541–548. doi:10.1038/21119. ISSN 1476-4687.
{{cite journal}}: Check date values in:|date=(help) - ^ Colson, Philippe; La Scola, Bernard; Levasseur, Anthony; Caetano-Anollés, Gustavo; Raoult, Didier (2017-04). "Mimivirus: leading the way in the discovery of giant viruses of amoebae". Nature Reviews Microbiology. 15 (4): 243–254. doi:10.1038/nrmicro.2016.197. ISSN 1740-1534. PMC 7096837. PMID 28239153.
{{cite journal}}: Check date values in:|date=(help)CS1 maint: PMC format (link) - ^ Pires de Souza, Gabriel Augusto; Rolland, Clara; Nafeh, Bariaa; La Scola, Bernard; Colson, Philippe (2021-02-10). "Giant virus-related sequences in the 5300-year-old Ötzi mummy metagenome". Virus Genes. 57 (2): 222–227. doi:10.1007/s11262-021-01823-2. ISSN 0920-8569.
- ^ a b "These giant viruses have more protein-making gear than any known virus". Science News. 2018-02-27. Retrieved 2021-04-07.
- ^ a b Rodrigues, Rodrigo Araújo Lima; Arantes, Thalita Souza; Oliveira, Graziele Pereira; dos Santos Silva, Ludmila Karen; Abrahão, Jônatas Santos (2019-01-01), Kielian, Margaret; Mettenleiter, Thomas C.; Roossinck, Marilyn J. (eds.), "Chapter Four - The Complex Nature of Tupanviruses", Advances in Virus Research, vol. 103, Academic Press, pp. 135–166, retrieved 2021-04-07
- ^ Sergeev, V. N.; Gerasimenko, L. M.; Zavarzin, G. A. (2002-11-01). "The Proterozoic History and Present State of Cyanobacteria". Microbiology. 71 (6): 623–637. doi:10.1023/A:1021415503436. ISSN 1608-3237.
- ^ a b c d e f g Oliveira, Graziele; Silva, Lorena; Leão, Thiago; Mougari, Said; da Fonseca, Flávio Guimarães; Kroon, Erna Geessien; La Scola, Bernard; Abrahão, Jônatas Santos (2019-01-17). "Tupanvirus-infected amoebas are induced to aggregate with uninfected cells promoting viral dissemination". Scientific Reports. 9 (1): 183. doi:10.1038/s41598-018-36552-4. ISSN 2045-2322.
- ^ a b c d e f g h Silva, Lorena C. F.; Rodrigues, Rodrigo Araújo Lima; Oliveira, Graziele Pereira; Dornas, Fabio Pio; La Scola, Bernard; Kroon, Erna G.; Abrahão, Jônatas S. (2019). "Microscopic Analysis of the Tupanvirus Cycle in Vermamoeba vermiformis". Frontiers in Microbiology. 10. doi:10.3389/fmicb.2019.00671. ISSN 1664-302X.
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