Betacoronavirus

{{Short description|Genus of viruses}} {{About-distinguish-text|the genus of coronavirus|the Beta variant of the SARS-CoV-2 virus that causes COVID-19}} {{Virusbox | image = 109239.fig.001abcd.png | image_alt = Murine coronavirus virion electron micrograph, schematic structure, and genome | image_caption = Murine coronavirus (MHV) virion electron micrograph, schematic structure, and genome | taxon = Betacoronavirus | synonyms = | synonyms_ref = | subdivision_ranks = Subgenera and species | subdivision = See text }}

'''''Betacoronavirus''''' (β-CoVs or Beta-CoVs) is one of four genera (''Alpha''-, ''Beta-'', ''Gamma-'', and ''Delta-'') of coronaviruses. Member viruses are enveloped, positive-strand RNA viruses that infect mammals, including humans. The natural reservoir for betacoronaviruses are bats and rodents. Rodents are the reservoir for the subgenus ''Embecovirus'', while bats are the reservoir for the other subgenera.<ref>{{Cite journal|last1=Wartecki|first1=Adrian|last2=Rzymski|first2=Piotr|date=June 2020|title=On the Coronaviruses and Their Associations with the Aquatic Environment and Wastewater|journal=Water|language=en|volume=12|issue=6|pages=1598|doi=10.3390/w12061598|doi-access=free}}</ref>

The coronavirus genera are each composed of varying viral lineages with the betacoronavirus genus containing four such lineages: A, B, C, D. In older literature, this genus is also known as "group 2 coronaviruses". The genus is in the subfamily ''Orthocoronavirinae'' in the family ''Coronaviridae'', of the order ''Nidovirales''.

The betacoronaviruses of the greatest clinical importance concerning humans are OC43 and HKU1 (which can cause the common cold) of lineage A, SARS-CoV-1 and SARS-CoV-2 (the causes of SARS and COVID-19 respectively) of lineage B,<ref>{{cite web |title=Phylogeny of SARS-like betacoronaviruses |url=https://nextstrain.org/groups/blab/sars-like-cov |website=nextstrain |access-date=18 January 2020}}</ref> and MERS-CoV (the cause of MERS) of lineage C. MERS-CoV is the first betacoronavirus belonging to lineage C that is known to infect humans.<ref>ProMED. MERS-CoV–Eastern Mediterranean (06) (http://www.promedmail.org/)</ref><ref>{{cite journal|last1=Memish|first1=Z. A.|last2=Zumla|first2=A. I.|last3=Al-Hakeem|first3=R. F.|last4=Al-Rabeeah|first4=A. A.|last5=Stephens|first5=G. M.|year=2013|title=Family Cluster of Middle East Respiratory Syndrome Coronavirus Infections|journal=New England Journal of Medicine|volume=368|issue=26|pages=2487–94|doi=10.1056/NEJMoa1303729|pmid=23718156|doi-access=free}}</ref>

==Etymology== The name "betacoronavirus" is derived from Ancient Greek βῆτα (''bē̂ta'', "the second letter of the Greek alphabet"), and κορώνη (korṓnē, “garland, wreath”), meaning crown, which describes the appearance of the surface projections seen under electron microscopy that resemble a solar corona. This morphology is created by the viral spike (S) peplomers, which are proteins that populate the surface of the virus and determine host tropism. The order ''Nidovirales'' is named for the Latin ''nidus'', which means 'nest'. It refers to this order's production of a 3′-coterminal nested set of subgenomic mRNAs during infection.<ref name="Woo10" />

== Structure == alt=|thumb|MERS-CoV: structure, attachment, entrance, and genomic composition

Several structures of the spike proteins have been resolved. The receptor binding domain in the alpha- and betacoronavirus spike protein is cataloged as {{InterPro|IPR018548}}.<ref>{{cite journal|last1=Huang|first1=C|last2=Qi|first2=J|last3=Lu|first3=G|last4=Wang|first4=Q|last5=Yuan|first5=Y|last6=Wu|first6=Y|last7=Zhang|first7=Y|last8=Yan|first8=J|last9=Gao|first9=GF|date=1 November 2016|title=Putative Receptor Binding Domain of Bat-Derived Coronavirus HKU9 Spike Protein: Evolution of Betacoronavirus Receptor Binding Motifs.|journal=Biochemistry|volume=55|issue=43|pages=5977–88|doi=10.1021/acs.biochem.6b00790|pmid=27696819|pmc=7075523|doi-access=free}}</ref> The spike protein, a type 1 fusion machine, assembles into a trimer ({{PDB|3jcl|6acg}}); its core structure resembles that of paramyxovirus F (fusion) proteins.<ref>{{cite journal|last1=Walls|first1=Alexandra C.|last2=Tortorici|first2=M. Alejandra|last3=Bosch|first3=Berend-Jan|last4=Frenz|first4=Brandon|last5=Rottier|first5=Peter J. M.|last6=DiMaio|first6=Frank|last7=Rey|first7=Félix A.|last8=Veesler|first8=David|date=8 February 2016|title=Cryo-electron microscopy structure of a coronavirus spike glycoprotein trimer|journal=Nature|volume=531|issue=7592|pages=114–117|bibcode=2016Natur.531..114W|doi=10.1038/nature16988|pmc=5018210|pmid=26855426}}</ref> The receptor usage is not very conserved; for example, among ''Sarbecovirus'', only a sub-lineage containing SARS share the ACE2 receptor.

The viruses of subgenera ''Embecovirus'' differ from all others in the genus in that they have an additional shorter (8 nm) spike-like protein called hemagglutinin esterase (HE) ({{UniProt|P15776}}). It is believed to have been acquired from influenza C virus.<ref name="Woo10" /><ref>{{Cite journal|last1=Bakkers|first1=Mark J. G.|last2=Lang|first2=Yifei|last3=Feitsma|first3=Louris J.|last4=Hulswit|first4=Ruben J. G.|last5=Poot|first5=Stefanie A. H. de|last6=Vliet|first6=Arno L. W. van|last7=Margine|first7=Irina|last8=Groot-Mijnes|first8=Jolanda D. F. de|last9=Kuppeveld|first9=Frank J. M. van|last10=Langereis|first10=Martijn A.|last11=Huizinga|first11=Eric G.|date=2017-03-08|title=Betacoronavirus Adaptation to Humans Involved Progressive Loss of Hemagglutinin-Esterase Lectin Activity|journal=Cell Host & Microbe|language=en|volume=21|issue=3|pages=356–366|doi=10.1016/j.chom.2017.02.008|issn=1931-3128|pmid=28279346|pmc=7104930|doi-access=free}}</ref>

==Genome== [[File:Temi_a_1736644_f0001_oc_(1).jpg|thumb|Genomes of alphacoronaviruses and betacoronaviruses]] Coronaviruses have a large genome size that ranges from 26 to 32 kilobases. The overall structure of β-CoV genome is similar to that of other CoVs, with an ORF1ab replicase polyprotein (''rep'', ''pp1ab'') preceding other elements. This polyprotein is cleaved into 16 nonstructural proteins (see UniProt annotation of SARS ''rep'', {{UniProt|P0C6X7}}).

As of May 2013, GenBank has 46 published complete genomes of the α- (group 1), β- (group 2), γ- (group 3), and δ- (group 4) CoVs.<ref name="lin">{{cite journal|last1=Cotten|first1=Matthew|last2=Lam|first2=Tommy T.|last3=Watson|first3=Simon J.|last4=Palser|first4=Anne L.|last5=Petrova|first5=Velislava|last6=Grant|first6=Paul|last7=Pybus|first7=Oliver G.|last8=Rambaut|first8=Andrew|last9=Guan|first9=Yi|last10=Pillay|first10=Deenan|last11=Kellam|first11=Paul|date=2013-05-19|title=Full-Genome Deep Sequencing and Phylogenetic Analysis of Novel Human Betacoronavirus|journal=Emerging Infectious Diseases|volume=19|issue=5|pages=736–42B|doi=10.3201/eid1905.130057|pmc=3647518|pmid=23693015|last12=Nastouli|first12=Eleni|author-link12=Eleni Nastouli}}</ref>

==Recombination== Genetic recombination can occur when two or more viral genomes are present in the same host cell. The dromedary camel Beta-CoV HKU23 exhibits genetic diversity in the African camel population.<ref name="So2019">{{cite journal | last1 = So | first1 = RTY | display-authors = etal | year = 2019 | title = Diversity of Dromedary Camel Coronavirus HKU23 in African Camels Revealed Multiple Recombination Events among Closely Related Betacoronaviruses of the Subgenus Embecovirus | journal = J Virol | volume = 93| issue = 23| page = | pmid = 31534035 | doi = 10.1128/JVI.01236-19 | pmc = 6854494 }}</ref> Contributing to this diversity are several recombination events that had taken place in the past between closely related betacoronaviruses of the subgenus ''Embecovirus''.<ref name="So2019" /> Also the betacoronavirus, Human SARS-CoV, appears to have had a complex history of recombination between ancestral coronaviruses that were hosted in several different animal groups.<ref>{{cite journal | last1 = Stanhope | first1 = MJ | last2 = Brown | first2 = JR | last3 = Amrine-Madsen | first3 = H | year = 2004 | title = Evidence from the evolutionary analysis of nucleotide sequences for a recombinant history of SARS-CoV | journal = Infect Genet Evol| volume = 4 | issue = 1| pages = 15–9 | pmid = 15019585 | doi = 10.1016/j.meegid.2003.10.001 | pmc = 7128439 }}</ref><ref name="Zhang2005">{{cite journal | last1 = Zhang | first1 = XW | last2 = Yap | first2 = YL | last3 = Danchin | first3 = A | year = 2005 | title = Testing the hypothesis of a recombinant origin of the SARS-associated coronavirus | journal = Arch Virol | volume = 150 | issue = 1| pages = 1–20 | pmid = 15480857 | doi = 10.1007/s00705-004-0413-9 | pmc = 7087341 }}</ref>

==Pathogenesis== thumb|Replication cycle of viruses of genus ''Betacoronavirus'' Alpha- and betacoronaviruses mainly infect bats, but they also infect other species like humans, camels, and rodents.<ref name="b1">{{cite journal|last1=Woo|first1=P. C.|last2=Wang|first2=M.|last3=Lau|first3=S. K.|last4=Xu|first4=H.|last5=Poon|first5=R. W.|last6=Guo|first6=R.|last7=Wong|first7=B. H.|last8=Gao|first8=K.|last9=Tsoi|first9=H. W.|last10=Huang|first10=Y.|last11=Li|first11=K. S.|year=2007|title=Comparative analysis of twelve genomes of three novel group 2c and group 2d coronaviruses reveals unique group and subgroup features|journal=Journal of Virology|volume=81|issue=4|pages=1574–85|doi=10.1128/JVI.02182-06|pmc=1797546|pmid=17121802|first13=K. H.|last14=Zheng|first14=B. J.|last15=Yuen|first15=K. Y.|last12=Lam|last13=Chan|first12=C. S.}}</ref><ref name="b2">{{cite journal|last1=Lau|first1=S. K.|last2=Woo|first2=P. C.|last3=Yip|first3=C. C.|last4=Fan|first4=R. Y.|last5=Huang|first5=Y.|last6=Wang|first6=M.|last7=Guo|first7=R.|last8=Lam|first8=C. S.|last9=Tsang|first9=A. K.|last10=Lai|first10=K. K.|last11=Chan|first11=K. H.|year=2012|title=Isolation and characterization of a novel Betacoronavirus subgroup A coronavirus, rabbit coronavirus HKU14, from domestic rabbits|journal=Journal of Virology|volume=86|issue=10|pages=5481–96|doi=10.1128/JVI.06927-11|pmc=3347282|pmid=22398294|last13=Zheng|first13=B. J.|last14=Yuen|first14=K. Y.|first12=X. Y.|last12=Che}}</ref><ref>{{cite journal|last1=Zhang|first1=Wei|last2=Zheng|first2=Xiao-Shuang|last3=Agwanda|first3=Bernard|last4=Ommeh|first4=Sheila|last5=Zhao|first5=Kai|last6=Lichoti|first6=Jacqueline|last7=Wang|first7=Ning|last8=Chen|first8=Jing|last9=Li|first9=Bei|last10=Yang|first10=Xing-Lou|last11=Mani|first11=Shailendra|date=24 October 2019|title=Serological evidence of MERS-CoV and HKU8-related CoV co-infection in Kenyan camels|journal=Emerging Microbes & Infections|volume=8|issue=1|pages=1528–1534|doi=10.1080/22221751.2019.1679610|pmc=6818114|pmid=31645223|last16=Yan|first15=Samson Omondi|last12=Ngeiywa|first12=Kisa-Juma|first13=Yan|last14=Hu|first14=Ben|last15=Onyuok|first20=Zheng-Li|first16=Bing|last20=Shi|first19=Peng|last19=Zhou|first18=Lin-Fa|last18=Wang|first17=Danielle E.|last17=Anderson|last13=Zhu}}</ref> Betacoronaviruses that have caused epidemics in humans generally induce fever and respiratory symptoms. They include:

* SARS-CoV, causing SARS. * MERS-CoV, causing MERS. * SARS-CoV-2, causing COVID-19.

==Classification== [[File:Journal.pone.0194527.g009.png|thumb|Phylogenetic tree of the lineages of genus ''Betacoronavirus'' with detail for SARS-CoV and MERS-CoV]]

Within the genus ''Betacoronavirus'' (Group 2 CoV), four subgenera or lineages (A, B, C, and D) have traditionally been recognized.<ref name=Woo10>{{Cite journal|last1=Woo|first1=Patrick C. Y.|last2=Huang|first2=Yi|last3=Lau|first3=Susanna K. P.|last4=Yuen|first4=Kwok-Yung|date=2010-08-24|title=Coronavirus Genomics and Bioinformatics Analysis|journal=Viruses|volume=2|issue=8|pages=1804–20|doi=10.3390/v2081803 |pmc=3185738|pmid=21994708|doi-access=free}}</ref> The four lineages have also been named using Greek letters or numerically.<ref name="lin" /> A fifth subgenus, ''Hibecovirus'', was added more recently.<ref name="Wong2019">{{cite journal |first1=Antonio C.P. |last1=Wong |first2=Xin |last2=Li |first3=Susanna K.P. |last3=Lau |first4=Patrick C.Y. |last4=Woo |title=Global Epidemiology of Bat Coronaviruses |journal=Viruses |volume=11 |issue=2 |pages=174 |year=2019 |doi=10.3390/v11020174 |pmid=30791586 |pmc=6409556|doi-access=free }}</ref> Member subgenera and species include:<ref>{{cite web|title=Virus Taxonomy: 2024 Release|url=https://ictv.global/taxonomy|publisher=International Committee on Taxonomy of Viruses|access-date=9 April 2025}}</ref><ref>{{cite web |title=Species List: ''Coronaviridae'' |url=https://ictv.global/report/chapter/coronaviridae/taxonomy/coronaviridae |publisher=International Committee on Taxonomy of Viruses |access-date=9 April 2025}}</ref>

==See also== * Animal viruses

==References== {{Reflist|2}}

==External links== * [https://web.archive.org/web/20070309144307/http://www-micro.msb.le.ac.uk/3035/Coronaviruses.html Coronaviruses] * [http://viralzone.expasy.org/all_by_species/764.html '''Viralzone''': ''Betacoronavirus''] * [https://web.archive.org/web/20130312042413/http://www.viprbrc.org/brc/home.do?decorator=corona Virus Pathogen Database and Analysis Resource (ViPR): ''Coronaviridae'']

Category:Betacoronaviruses Category:Virus genera Category:Coronaviruses