Betatorquevirus

Edit links
From Wikipedia, the free encyclopedia
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.
Betatorquevirus
Virus classification Edit this classification
(unranked): Virus
Family: Anelloviridae
Genus: Betatorquevirus

Betatorquevirus is a genus of viruses in the family Anelloviridae, in group II in the Baltimore classification. The genus Betatorquevirus includes all "torque teno mini viruses" (TTMV), numbered from 1 to 38 as 38 species.

Taxonomy

The genus contains the following species:[1]

Initial discovery

The discovery of TTMV, like the original Torque Teno virus (TTV) isolate, was accidental. After TTV was isolated in 1997 from a Japanese patient, primers were created to study TTV in more detail. TTV-specific primers used in PCR of human plasma samples yielded sequences that partially matched that of TTV, but were noticeably shorter.[2][3] TTV was eventually understood to have a genome of 3.6–3.9 kb, while TTMV has a genome of 2.8–2.9 kb. Another TT-like virus later isolated in 2007, Torque teno midi virus or TTMDV, has a genome of 3.2 kb.[3]

Genome and capsid

TTMV shares similar morphologic features with the other human anelloviruses. The capsid has a T=1 icosahedral symmetry.[2] The virion does not have a lipid envelope and is thus "naked", making it an extremely simple virus. It is estimated that the virion is a little less than 30 nm in diameter.[2][3]

The genome is circular and made of single-stranded DNA of negative polarity. It is 2.86–2.91 kilobases long.[2] Anelloviruses are known for having 3 or 4 overlapping, nested open reading frames; TTMV has 3 ORF's that overlap.[2][4] ORF-2 and ORF-3 overlap with ORF-1 at opposite ends. For TTMV, ORF-1 is about 663 residues and ORF-2 is about 91 residues long.[2] There is a highly conserved 130-nt region just downstream of the TATA box.[3]

Phylogeny & spread

TTMV is highly divergent.[2][3] The first phylogenetic tree created from TTMV genomic sequences revealed a large cluster of strains; ORF-1 had divergences of over 42% at the nucleotide level and over 67% at the amino acid level.[2]

TTMV is also highly prevalent, like other human anelloviruses. Subsequent research after it was discovered has yielded the prevalence of TTMV DNA among blood donors to be 48%–72%.[3] It can likely infect a wide range of tissues, as it has been isolated from various body fluids and tissues, including saliva, feces, plasma/serum, PBMCs, bone marrow, spleen, pancreas, kidneys, nervous tissue, lymph nodes, semen, and cervical swabs.[2][3] Its exact transmission mechanism is unknown, but is thought to be possible by blood-borne, sexual, fecal-oral, and respiratory routes.[2]

Recent studies have shown that humans can have multiple infections of TT viruses.[3][4]

Clinical

Though TTVs are potentially associated with dieases and their pathogenicity has been debated since their discovery, TTMV is not currently known as an explicit cause of any human disease.[2] TTMV has been isolated from a number of parapneumonic empyema.[5] However, its clinical significance remains unclear.

References

  1. ^ "Virus Taxonomy: 2020 Release". International Committee on Taxonomy of Viruses (ICTV). March 2021. Retrieved 23 May 2021.
  2. ^ a b c d e f g h i j k Spandole, Sonia; Cimponeriu, Dănuţ; Berca, Lavinia Mariana; Mihăescu, Grigore (April 2015). "Human anelloviruses: an update of molecular, epidemiological and clinical aspects". Archives of Virology. 160 (4): 893–908. doi:10.1007/s00705-015-2363-9. PMID 25680568.
  3. ^ a b c d e f g h Okamoto, H (2009). "History of Discoveries and Pathogenicity of TT Viruses". TT Viruses. Current Topics in Microbiology and Immunology. Vol. 331. pp. 1–20. doi:10.1007/978-3-540-70972-5_1. ISBN 978-3-540-70971-8. PMID 19230554.
  4. ^ a b Zhang, Yu (May 6, 2016). "A novel species of torque teno mini virus (TTMV) in gingival tissue from chronic periodontitis patients". Scientific Reports. 6 (26739): 26739. Bibcode:2016NatSR...626739Z. doi:10.1038/srep26739. PMC 4879676. PMID 27221159.
  5. ^ Galmès J, Li Y, Rajoharison A, Ren L, Dollet S, Richard N, Vernet G, Javouhey E, Wang J, Telles JN, Paranhos-Baccalà G (2012) Potential implication of new torque teno mini viruses in parapneumonic empyema in children. Eur Respir J

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Betatorquevirus&oldid=1172318567"