Alphacoronavirus

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Alphacoronavirus
Virus classification e
(unranked): Virus
Realm: Riboviria
Phylum: incertae sedis
Order: Nidovirales
Family: Coronaviridae
Subfamily: Orthocoronavirinae
Genus: Alphacoronavirus
Subgenera and Species

Alphacoronaviruses (Alpha-CoV) are the first of the four genera, Alpha-, Beta-, Gamma-, and Deltacoronavirus in the subfamily Coronavirinae of the family Coronaviridae. Coronaviruses are enveloped, positive-sense, single-stranded RNA viruses that include both human and zoonotic species. Within this subfamily, viruses have spherical virions with club-shaped surface projections and a core shell. The name is from the Latin corona, meaning crown, which describes the appearance of the projections seen under electron microscopy that resemble a solar corona. This genus contains what were previously considered phylogroup 1 coronaviruses.[1]

Both the Alpha- and Betacoronavirus lineages descend from the bat gene pool.[2][3][4]

Virology[edit]

The virion is enveloped and spherical measuring 120–160 nm in diameter and a core shell of about 65 nm. Glycoproteins and trimers form large surface projections which create the appearance of solar corona from which it takes its name. The genome is positive-sense, single-stranded RNA with a length of 27 to 29 kilobases and a 3’-polyA tail. Two large, overlapping ORFs at the 5'-end of the genome encode the major non-structural proteins expressed as a fusion protein by ribosomal frameshift. These include regions with protease, helicase and RNA polymerase motifs. There are 7 other genes downstream which encode structural proteins. These are expressed from a 3'-coterminal nested set of subgenomic mRNAs.

Spike and receptor[edit]

This genus, like other coronaviruses, has a spike protein with a type II fusion machine (S2) and a receptor-binding domain (S1). It assembles into a trimer. Unlike beta- and gammacoronaviruses, this protein is not cleaved into two halves.[5]

Both types of Alphacoronavirus 1, feline coronavirus (FCoV) and canine coronavirus (CCoV), are known to exist in two serotypes. Serotype II targets Aminopeptidase N, while the receptor for Serotype I is unknown. The difference is due to a different spike protein.[6] There is a common ancestor for FCoV and CCoV. This ancestor gradually evolved into FCoV I and CCoV I. An S protein from an unknown virus was recombined into the ancestor and gave rise to CCoV II. CCoV II once again recombined with FCoV to create FCoV II. CCoV II gradually evolved into TGEV. A spike deletion in TGEV creates PRCV. All these viruses are sorted into the subgenus Tegacovirus.[6]

Classification[edit]


See also[edit]

References[edit]

  1. ^ Decaro, Nicola (2011). "Alphacoronavirus". The Springer Index of Viruses. pp. 371–383. doi:10.1007/978-0-387-95919-1_56. ISBN 978-0-387-95918-4.
  2. ^ Woo, P. C.; Wang, M.; Lau, S. K.; Xu, H.; Poon, R. W.; Guo, R.; Wong, B. H.; Gao, K.; Tsoi, H. W.; Huang, Y.; Li, K. S.; Lam, C. S.; Chan, K. H.; Zheng, B. J.; Yuen, K. Y. (2007). "Comparative analysis of twelve genomes of three novel group 2c and group 2d coronaviruses reveals unique group and subgroup features". Journal of Virology. 81 (4): 1574–85. doi:10.1128/JVI.02182-06. PMC 1797546. PMID 17121802.
  3. ^ Lau, S. K.; Woo, P. C.; Yip, C. C.; Fan, R. Y.; Huang, Y.; Wang, M.; Guo, R.; Lam, C. S.; Tsang, A. K.; Lai, K. K.; Chan, K. H.; Che, X. Y.; Zheng, B. J.; Yuen, K. Y. (2012). "Isolation and characterization of a novel Betacoronavirus subgroup A coronavirus, rabbit coronavirus HKU14, from domestic rabbits". Journal of Virology. 86 (10): 5481–96. doi:10.1128/JVI.06927-11. PMC 3347282. PMID 22398294.
  4. ^ Lau, S. K.; Poon, R. W.; Wong, B. H.; Wang, M.; Huang, Y.; Xu, H.; Guo, R.; Li, K. S.; Gao, K.; Chan, K. H.; Zheng, B. J.; Woo, P. C.; Yuen, K. Y. (2010). "Coexistence of different genotypes in the same bat and serological characterization of Rousettus bat coronavirus HKU9 belonging to a novel Betacoronavirus subgroup". Journal of Virology. 84 (21): 11385–94. doi:10.1128/JVI.01121-10. PMC 2953156. PMID 20702646.
  5. ^ Wrapp, Daniel; McLellan, Jason S.; Gallagher, Tom (13 November 2019). "The 3.1-Angstrom Cryo-electron Microscopy Structure of the Porcine Epidemic Diarrhea Virus Spike Protein in the Prefusion Conformation". Journal of Virology. 93 (23). doi:10.1128/JVI.00923-19.
  6. ^ a b Jaimes, Javier A.; Millet, Jean K.; Stout, Alison E.; André, Nicole M.; Whittaker, Gary R. (10 January 2020). "A Tale of Two Viruses: The Distinct Spike Glycoproteins of Feline Coronaviruses". Viruses. 12 (1): 83. doi:10.3390/v12010083.
  7. ^ Cruz JL, Sola I, Becares M, Alberca B, Plana J, Enjuanes L, Zuñiga S (June 2011). "Coronavirus gene 7 counteracts host defenses and modulates virus virulence". PLoS Pathogens. 7 (6): e1002090. doi:10.1371/journal.ppat.1002090. PMC 3111541. PMID 21695242.
  8. ^ Cruz JL, Becares M, Sola I, Oliveros JC, Enjuanes L, Zúñiga S (September 2013). "Alphacoronavirus protein 7 modulates host innate immune response". Journal of Virology. 87 (17): 9754–67. doi:10.1128/JVI.01032-13. PMC 3754097. PMID 23824792.

External links[edit]



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