View source for Coronavirus

{{Short description|Subfamily of viruses in the family Coronaviridae}}
{{cs1 config|name-list-style=vanc|display-authors=6}}
{{About|the group of viruses|the disease involved in the COVID-19 pandemic|COVID-19|the virus that causes this disease|SARS-CoV-2}}
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{{Use dmy dates|date=March 2022|cs1-dates=y}}
{{Virusbox
| image = Coronavirus._SARS-CoV-2.png
| image_alt = Group member SARS-CoV-2
| image_caption = Group member [[SARS-CoV-2]]
{{Collapsible list
|title = Illustration key:
|{{leftlegend|#005db7|Blue: [[lipid bilayer]] [[Viral envelope|envelope]]}}
{{leftlegend|#02e6ff|Light blue: [[coronavirus spike protein|spike (S) glycoprotein]]}}
{{leftlegend|#ff0c78|Red: [[coronavirus envelope protein|envelope (E) proteins]]}}
{{leftlegend|#9bff57|Green: [[coronavirus membrane protein|membrane (M) proteins]] .}}
{{leftlegend|#fe8a00|Orange: [[glycan]]}}
}}
| taxon = Orthocoronavirinae
| subdivision_ranks =
| subdivision_ref = <ref name=ICTV2018b>{{cite web |title=Virus Taxonomy: 2018b Release |url=https://ictv.global/taxonomy |website=International Committee on Taxonomy of Viruses (ICTV) |access-date=24 January 2020 |language=en |date=March 2019 |archive-url=https://web.archive.org/web/20180304035352/https://talk.ictvonline.org/taxonomy/ |archive-date=4 March 2018 |url-status=live}}</ref>
| subdivision =
{{Collapsible list
| bullets = true
| title = <small>Information:</small>
| ''[[Alphacoronavirus]]''
| ''[[Betacoronavirus]]''
| ''[[Gammacoronavirus]]''
| ''[[Deltacoronavirus (genus)|Deltacoronavirus]]''}}
| synonyms = *''Coronavirinae''
| synonyms_ref = <ref name="2017.012-015S">{{cite web |title=2017.012-015S |url=https://ictv.global/ictv/proposals/2017.012_015S.A.v1.Nidovirales.zip |website=International Committee on Taxonomy of Viruses (ICTV) |access-date=24 January 2020 |language=en |format=xlsx |date=October 2018 |archive-url=https://web.archive.org/web/20190514162836/https://talk.ictvonline.org/ictv/proposals/2017.012_015S.A.v1.Nidovirales.zip |archive-date=14 May 2019 |url-status=live}}</ref><ref name="OrthocoronavirinaeICTV">{{cite web |title=ICTV Taxonomy history: ''Orthocoronavirinae'' |url=https://ictv.global/taxonomy/taxondetails?taxnode_id=201851847 |website=International Committee on Taxonomy of Viruses (ICTV) |access-date=24 January 2020 |language=en}}</ref>
}}
'''Coronaviruses''' are a group of related [[RNA viruses]] that cause diseases in [[mammal]]s and [[bird]]s. In humans and birds, they cause [[respiratory tract infection]]s that can range from mild to lethal. Mild illnesses in humans include some cases of the [[common cold]] (which is also caused by other viruses, predominantly [[rhinovirus]]es), while more lethal varieties can cause [[SARS]], [[MERS]] and [[COVID-19]]. In cows and pigs, they cause [[diarrhea]]; while in mice, they cause [[hepatitis]] and [[encephalomyelitis]].

Coronaviruses constitute the [[subfamily]] '''''Orthocoronavirinae''''', in the family ''[[Coronaviridae]]'', order ''[[Nidovirales]],'' and realm ''[[Riboviria]]''.<ref name="OrthocoronavirinaeICTV" /><ref name="FanZhao2019" /> They are [[enveloped virus]]es with a [[Positive-strand RNA virus|positive-sense single-stranded]] [[RNA]] [[genome]] and a [[nucleocapsid]] of helical symmetry.<ref>{{cite book | vauthors = Cherry J, Demmler-Harrison GJ, Kaplan SL, Steinbach WJ, Hotez PJ |title=Feigin and Cherry's Textbook of Pediatric Infectious Diseases |date=2017 |publisher=Elsevier Health Sciences |isbn=978-0-323-39281-5 |page=PT6615 |url=https://books.google.com/books?id=z-ZIDwAAQBAJ&pg=PT6615 |language=en}}</ref> The [[genome size]] of coronaviruses ranges from approximately 26 to 32 [[kilobase]]s, one of the largest among RNA viruses.<ref name=":1">{{cite journal | vauthors = Woo PC, Huang Y, Lau SK, Yuen KY | title = Coronavirus genomics and bioinformatics analysis | journal = Viruses | volume = 2 | issue = 8 | pages = 1804–20 | date = August 2010 | pmid = 21994708 | pmc = 3185738 | doi = 10.3390/v2081803 | bibcode = 2010Virus...2.1804W | quote = Coronaviruses possess the largest genomes [26.4 kb (ThCoV HKU12) to 31.7 kb (SW1)] among all known RNA viruses (Figure 1) [2,13,16]. | doi-access = free }}</ref> They have characteristic club-shaped [[Spike protein|spikes]] that project from their surface, which in [[electron micrograph]]s create an image reminiscent of the [[stellar corona]], from which their name derives.<ref name=":2">{{Cite journal|vauthors=Almeida JD, Berry DM, Cunningham CH, Hamre D, Hofstad MS, Mallucci L, McIntosh K, Tyrrell DA |date=November 1968 |title=Virology: Coronaviruses  |journal=Nature |volume=220 |issue=5168 |page=650 | pmc=7086490|doi=10.1038/220650b0 |bibcode=1968Natur.220..650. |quote=[T]here is also a characteristic "fringe" of projections 200 A long, which are rounded or petal shaped{{nbsp}}... This appearance, recalling the solar corona, is shared by mouse hepatitis virus and several viruses recently recovered from man, namely strain B814, 229E and several others.|doi-access=free }}</ref>

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== Etymology ==
The name "coronavirus" is derived from Latin ''[[wikt:corona#Latin|corona]]'', meaning "crown" or "wreath", itself a borrowing from [[Ancient Greek|Greek]] {{lang|grc|κορώνη}} ''korṓnē'', "garland, wreath".<ref>{{cite web |title=Definition of Coronavirus by Merriam-Webster|url=https://www.merriam-webster.com/dictionary/coronavirus|archive-url=https://web.archive.org/web/20200323161218/https://www.merriam-webster.com/dictionary/coronavirus|publisher=Merriam-Webster|access-date=24 March 2020|archive-date=23 March 2020|url-status=live}}</ref><ref>{{cite web |title=Definition of Corona by Merriam-Webster|url=https://www.merriam-webster.com/dictionary/corona|archive-url=https://web.archive.org/web/20200324161709/https://www.merriam-webster.com/dictionary/corona|publisher=Merriam-Webster|access-date=24 March 2020|archive-date=24 March 2020|url-status=live}}</ref> The name was coined by [[June Almeida]] and [[David Tyrrell (physician)|David Tyrrell]] who first observed and studied human coronaviruses.<ref name=":10" /> The word was first used in print in 1968 by an informal group of virologists in the journal ''[[Nature (journal)|Nature]]'' to designate the new family of viruses.<ref name=":2" /> The name refers to the characteristic appearance of [[virion]]s (the infective form of the virus) by [[electron microscopy]], which have a fringe of large, bulbous surface projections creating an image reminiscent of the [[solar corona]] or halo.<ref name=":2" /><ref name=":10">{{Cite book|last1=Tyrrell|first1=David Arthur John |last2=Fielder |first2=Michael |url=https://books.google.com/books?id=ALxG44e0bfAC&q=june |title=Cold Wars: The Fight Against the Common Cold |date=2002 |publisher=Oxford University Press |isbn=978-0-19-263285-2|page=96|language=en|quote=We looked more closely at the appearance of the new viruses and noticed that they had a kind of halo surrounding them. Recourse to a dictionary produced the Latin equivalent, corona, and so the name coronavirus was born.}}</ref> This [[Morphology (biology)|morphology]] is created by the viral spike [[peplomer]]s, which are [[proteins]] on the surface of the virus.<ref>{{cite book |last1=Sturman |first1=Lawrence S. |last2=Holmes |first2=Kathryn V. |title=The Molecular Biology of Coronaviruses |series=Advances in Virus Research |date=1983 |volume=28 |pages=35–112 |doi=10.1016/s0065-3527(08)60721-6 |pmid=6362367 |pmc=7131312 |isbn=978-0-12-039828-7 | quote = [T]hese viruses displayed a characteristic fringe of large, distinctive, petal-shaped peplomers or spikes which resembled a crown, like the ''corona spinarum'' in religious art; hence the name coronaviruses. | doi-access = free }}</ref>

The scientific name ''Coronavirus'' was accepted as a genus name by the International Committee for the Nomenclature of Viruses (later renamed [[International Committee on Taxonomy of Viruses]]) in 1971.<ref name=":02">{{Cite journal|last=Lalchhandama|first=Kholhring|date=2020|title=The chronicles of coronaviruses: the bronchitis, the hepatitis and the common cold|journal=Science Vision|language=en|volume=20|issue=1|pages=43–53|doi=10.33493/scivis.20.01.04|doi-access=free}}</ref> As the number of new species increased, the genus was split into four genera, namely ''[[Alphacoronavirus]]'', ''[[Betacoronavirus]]'', ''[[Deltacoronavirus (genus)|Deltacoronavirus]]'', and ''[[Gammacoronavirus]]'' in 2009.<ref>{{cite journal | vauthors = Carstens EB | title = Ratification vote on taxonomic proposals to the International Committee on Taxonomy of Viruses (2009) | journal = Archives of Virology | volume = 155 | issue = 1 | pages = 133–46 | date = 2010 | pmid = 19960211 | pmc = 7086975 | doi = 10.1007/s00705-009-0547-x | bibcode = 2010ArcV..155..133C }}</ref> The common name coronavirus is used to refer to any member of the subfamily ''Orthocoronavirinae''.<ref name="FanZhao2019">{{cite journal | vauthors = Fan Y, Zhao K, Shi ZL, Zhou P | title = Bat Coronaviruses in China | journal = Viruses | volume = 11 | issue = 3 | page = 210 | date = March 2019 | pmid = 30832341 | pmc = 6466186 | doi = 10.3390/v11030210 | bibcode = 2019Virus..11..210F | doi-access = free }}</ref> As of 2020, 45 species are officially recognised.<ref>{{Cite web|title=International Committee on Taxonomy of Viruses (ICTV)|url=https://ictv.global/taxonomy|access-date=14 September 2020|website=talk.ictvonline.org|language=en}}</ref>

== History ==
{{Main|History of coronavirus}}
[[File:TEM of avian infectious bronchitis virus rotated cropped.jpg|thumb|Colorized [[transmission electron micrograph]] of coronavirus 229E]]
A number of 2021 studies found that the [[most recent common ancestor]] (MRCA) for Coronaviruses may have emerged around 21,000–25,000 years ago in [[East Asia]], during the earliest uncovered Coronavirus outbreak. Researchers found that 42 Coronavirus-specific virus-interacting proteins (CoV-VIPs) in East Asian populations were most likely selected for during this ancient outbreak, with the viruses driving an adaptive response in the ancestors of East Asians.<ref name="ancient viral epidemic">{{cite journal |title=An ancient viral epidemic involving host coronavirus interacting genes more than 20,000 years ago in East Asia |journal=Current Biology |date=2021 |volume=31 |issue=16 |pages=3504–3514.e9 |doi=10.1016/j.cub.2021.05.067 |pmid=34171302 |pmc=8223470 |bibcode=2021CBio...31E3504S | vauthors = Souilmi Y, Lauterbur ME, Tobler R, Huber CD, Johar AS, Moradi SV, Johnston WA, Krogan NJ, Alexandrov K, Enard D }}</ref><ref name="21,000 years ago">{{cite web|url=https://www.ox.ac.uk/news/2021-09-02-coronavirus-epidemics-first-hit-more-21000-years-ago|title=Coronavirus Epidemics first hit more than 21,000 years ago|author=|work=Oxford University News|date=2 September 2021|access-date=27 November 2025}}</ref> The four known genera of Coronaviruses, ''Alphacoronavirus'', ''Betacoronavirus'', ''Gammacoronavirus'', and ''Deltacoronavirus'' split up around 2,400 to 3,300 years ago into bat and avian coronavirus ancestors. Bat coronaviruses gave rise to the species of ''Alphacoronavirus'' and ''Betacoronavirus'' that infect mammals, while avian coronavirus produced those of ''Gammacoronavirus'' and ''Deltacoronavirus'' that infect birds.<ref name="Woo2012" />

The earliest reports of a coronavirus infection in animals occurred in the late 1920s, when an acute respiratory infection of domesticated chickens emerged in North America.<ref>{{Cite journal| vauthors = Estola T |date=1970|title=Coronaviruses, a New Group of Animal RNA Viruses|journal=Avian Diseases|volume=14|issue=2|pages=330–336|doi=10.2307/1588476|jstor=1588476|pmid=4316767 }}</ref> Arthur Schalk and M.C. Hawn in 1931 made the first detailed report which described a new [[Avian infectious bronchitis|respiratory infection of chickens]] in [[North Dakota]]. The infection of new-born chicks was characterized by gasping and listlessness with high mortality rates of 40–90%.<ref>{{Cite journal |last=Fabricant |first=Julius |date=1998|title=The Early History of Infectious Bronchitis|journal=Avian Diseases|volume=42|issue=4|pages=648–650|doi=10.2307/1592697|jstor=1592697|pmid=9876830 }}</ref> Leland David Bushnell and Carl Alfred Brandly isolated the virus that caused the infection in 1933.<ref name=":22">{{Cite journal|vauthors=Bushnell LD, Brandly CA|date=1933|title=Laryngotracheitis in chicks|journal=Poultry Science|language=en|volume=12|issue=1|pages=55–60|doi=10.3382/ps.0120055|doi-access=free}}</ref> The virus was then known as [[Avian coronavirus|infectious bronchitis virus]] (IBV). Charles D. Hudson and Fred Robert Beaudette cultivated the virus for the first time in 1937.<ref name=":11">{{cite encyclopedia |last=Decaro|first=Nicola |title=Gammacoronavirus‡: Coronaviridae |entry=Gammacoronavirus|date=2011 |encyclopedia =The Springer Index of Viruses|pages=403–413|editor-last=Tidona|editor-first=Christian |editor2-last=Darai |editor2-first=Gholamreza |publisher=Springer|language=en|doi=10.1007/978-0-387-95919-1_58|isbn=978-0-387-95919-1|pmc=7176155 }}</ref> The specimen came to be known as the Beaudette strain. In the late 1940s, two more animal coronaviruses, JHM that causes brain disease (murine encephalitis) and [[Murine coronavirus|mouse hepatitis virus]] (MHV) that causes hepatitis in mice were discovered.<ref name=":3">{{Cite book| vauthors = McIntosh K |title=Current Topics in Microbiology and Immunology / Ergebnisse der Mikrobiologie und Immunitätsforschung|date=1974| veditors = Arber W, Haas R, Henle W, Hofschneider PH, Jerne NK, Koldovský P, Koprowski H, Maaløe O, Rott R |chapter=Coronaviruses: A Comparative Review|language=en|location=Berlin, Heidelberg |publisher=Springer |page=87 |doi=10.1007/978-3-642-65775-7_3 |isbn=978-3-642-65775-7 }}</ref> It was not realized at the time that these three different viruses were related.<ref>{{Cite news|url=https://www.lemonde.fr/blog/realitesbiomedicales/2020/03/27/il-etait-une-fois-les-coronavirus|title=Il était une fois les coronavirus|date=27 March 2020|work=Réalités Biomédicales|access-date=18 April 2020|language=fr-FR}}</ref><ref name=":02" />

Human coronaviruses were discovered in the 1960s<ref>{{cite journal | vauthors = Kahn JS, McIntosh K | title = History and recent advances in coronavirus discovery | journal = The Pediatric Infectious Disease Journal | volume = 24 | issue = 11 Suppl | pages = S223–7, discussion S226 | date = November 2005 | pmid = 16378050 | doi = 10.1097/01.inf.0000188166.17324.60 | doi-access = free }}</ref><ref>{{cite journal |title=Covid-19: First coronavirus was described in ''The BMJ'' in 1965 |journal=BMJ |date=2020 |volume=369 |article-number=m1547 |doi=10.1136/bmj.m1547 |pmid=32299810 | vauthors = Mahase E }}</ref> using two different methods in the United Kingdom and the United States.<ref>{{cite book |title=Viral Infections of Humans |chapter=Coronaviruses |date=1984 |pages=151–165 |doi=10.1007/978-1-4684-4727-9_7 |isbn=978-1-4684-4729-3 | vauthors = Monto AS }}</ref> E.C. Kendall, Malcolm Bynoe, and [[David Tyrrell (physician)|David Tyrrell]] working at the [[Common Cold Unit]] of the [[Medical Research Council (United Kingdom)|British Medical Research Council]] collected a unique [[common cold]] virus designated B814 in 1961.<ref name=":9">{{cite journal | vauthors = Kendall EJ, Bynoe ML, Tyrrell DA | title = Virus isolations from common colds occurring in a residential school | journal = British Medical Journal | volume = 2 | issue = 5297 | pages = 82–6 | date = July 1962 | pmid = 14455113 | pmc = 1925312 | doi = 10.1136/bmj.2.5297.82 }}</ref><ref>{{cite journal |last=Richmond |first=Caroline |date=18 June 2005|title=David Tyrrell|journal=BMJ: British Medical Journal |volume=330 |issue=7505 |page=1451 |doi=10.1136/bmj.330.7505.1451 |pmc=558394 }}</ref><ref>{{cite journal |title=Obituary Notices |journal=BMJ |date=1969 |volume=2 |issue=5660 |pages=827–829 |doi=10.1136/bmj.2.5660.827 }}</ref> The virus could not be cultivated using standard techniques which had successfully cultivated [[rhinovirus]]es, [[Adenoviridae|adenoviruses]] and other known common cold viruses. In 1965, Tyrrell and Bynoe successfully cultivated the novel virus by [[Serial passage|serially passing]] it through [[organ culture]] of [[Embryo|human embryonic]] [[trachea]].<ref>{{cite journal | vauthors = Tyrrell DA, Bynoe ML | title = Cultivation of a Novel Type of Common-Cold Virus in Organ Cultures | journal = British Medical Journal | volume = 1 | issue = 5448 | pages = 1467–70 | date = June 1965 | pmid = 14288084 | pmc = 2166670 | doi = 10.1136/bmj.1.5448.1467 }}</ref> The new cultivating method was introduced to the lab by Bertil Hoorn.<ref>{{Cite book|last1=Tyrrell|first1=David Arthur John |last2=Fielder|first2=Michael |url=https://books.google.com/books?id=ALxG44e0bfAC&q=Bertil%20Hoorn|title=Cold Wars: The Fight Against the Common Cold|date=2002|publisher=Oxford University Press|isbn=978-0-19-263285-2|pages=93–95|language=en}}</ref> The isolated virus when intranasally [[Inoculation|inoculated]] into volunteers caused a cold and was inactivated by [[ether]] which indicated it had a [[Viral envelope|lipid envelope]].<ref name=":9" /><ref>{{Cite book|last1=Hagan|first1=William Arthur |url=https://books.google.com/books?id=UtxUbXOfAFUC&q=Ether:+Enveloped+viruses+are+susceptible+to+ether.&pg=PA440|title=Hagan and Bruner's Microbiology and Infectious Diseases of Domestic Animals: With Reference to Etiology, Epizootiology, Pathogenesis, Immunity, Diagnosis, and Antimicrobial Susceptibility|last2=Bruner|first2=Dorsey William|last3=Gillespie|first3=James Howard|last4=Timoney|first4=John Francis|last5=Scott|first5=Fredric W.|last6=Barlough|first6=Jeffrey E. |date=1988|publisher=Cornell University Press|isbn=978-0-8014-1896-9|page=440|language=en}}</ref> Dorothy Hamre and John Procknow at the [[University of Chicago]] isolated a novel cold from medical students in 1962. They isolated and grew the virus in kidney [[tissue culture]], designating it 229E. The novel virus caused a cold in volunteers and, like B814, was inactivated by ether.<ref>{{cite journal |title=A New Virus Isolated from the Human Respiratory Tract |journal=Experimental Biology and Medicine |date=1966 |volume=121 |issue=1 |pages=190–193 |doi=10.3181/00379727-121-30734 |pmid=4285768 |bibcode=1966ExpBM.121..190H | vauthors = Hamre D, Procknow JJ }}</ref><ref>{{Cite web |last=Knapp |first=Alex |title=The Secret History Of The First Coronavirus |url=https://www.forbes.com/sites/alexknapp/2020/04/11/the-secret-history-of-the-first-coronavirus-229e/ |access-date=6 May 2020 |website=Forbes |language=en}}</ref>
[[File:TEM of coronavirus OC43.jpg|thumb|Transmission electron micrograph of organ cultured coronavirus OC43|right]]

Scottish virologist [[June Almeida]] at [[St Thomas' Hospital]] in London, collaborating with Tyrrell, compared the structures of IBV, B814 and 229E in 1967.<ref>{{Cite news|url=https://www.bbc.com/news/uk-scotland-52278716|title=The woman who discovered the first coronavirus|work=BBC News|date=14 April 2020}}</ref><ref>{{cite journal |title=June Almeida (Née Hart) |journal=BMJ |date=2008 |volume=336 |issue=7659 |pages=1511.1–1511 |doi=10.1136/bmj.a434 | vauthors = Almeida J }}</ref> Using [[Transmission electron microscopy|electron microscopy]] the three viruses were shown to be morphologically related by their general shape and distinctive club-like [[Peplomer|spikes]].<ref>{{cite journal | vauthors = Almeida JD, Tyrrell DA | title = The morphology of three previously uncharacterized human respiratory viruses that grow in organ culture | journal = The Journal of General Virology | volume = 1 | issue = 2 | pages = 175–8 | date = April 1967 | pmid = 4293939 | doi = 10.1099/0022-1317-1-2-175 | doi-access = free }}</ref> A research group at the [[National Institutes of Health|National Institute of Health]] the same year was able to isolate another member of this new group of viruses using organ culture and named one of the samples OC43 (OC for organ culture).<ref>{{cite journal | vauthors = McIntosh K, Becker WB, Chanock RM | title = Growth in suckling-mouse brain of "IBV-like" viruses from patients with upper respiratory tract disease | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 58 | issue = 6 | pages = 2268–73 | date = December 1967 | pmid = 4298953 | pmc = 223830 | doi = 10.1073/pnas.58.6.2268 | bibcode = 1967PNAS...58.2268M | doi-access = free }}</ref> Like B814, 229E, and IBV, the novel cold virus OC43 had distinctive club-like spikes when observed with the electron microscope.<ref>{{cite journal | vauthors = McIntosh K, Dees JH, Becker WB, Kapikian AZ, Chanock RM | title = Recovery in tracheal organ cultures of novel viruses from patients with respiratory disease | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 57 | issue = 4 | pages = 933–40 | date = April 1967 | pmid = 5231356 | pmc = 224637 | doi = 10.1073/pnas.57.4.933 | bibcode = 1967PNAS...57..933M | doi-access = free }}</ref><ref>{{Cite news|last=Times|first=Harold M. Schmeck Jr Special To the New York|url=https://www.nytimes.com/1967/05/05/archives/six-newly-discovered-viruses-may-explain-cold-strains-are-similar.html|title=Six Newly Discovered Viruses May Explain Cold; Strains Are Similar to Germ That Causes a Bronchial Infection in Chickens Believed to Be New Group|date=5 May 1967|work=The New York Times|access-date=25 April 2020|language=en-US }}</ref>

The IBV-like novel cold viruses were soon shown to be also morphologically related to the mouse hepatitis virus.<ref name=":3" /> This new group of viruses were named coronaviruses after their distinctive morphological appearance.<ref name=":2" /> [[Human coronavirus 229E]] and [[human coronavirus OC43]] continued to be studied in subsequent decades.<ref>{{cite book |title=The Coronaviridae |chapter=Human Coronavirus Infections |date=1995 |pages=389–401 |doi=10.1007/978-1-4899-1531-3_18 |isbn=978-1-4899-1533-7 | vauthors = Myint SH }}</ref><ref name="pmid23202515">{{cite journal | vauthors = Geller C, Varbanov M, Duval RE | title = Human coronaviruses: insights into environmental resistance and its influence on the development of new antiseptic strategies | journal = Viruses | volume = 4 | issue = 11 | pages = 3044–68 | date = November 2012 | pmid = 23202515 | pmc = 3509683 | doi = 10.3390/v4113044 | bibcode = 2012Virus...4.3044G | doi-access = free }}</ref> The coronavirus strain B814 was lost. It is not known which present human coronavirus it was.<ref>{{cite book |last1=Monto |first1=Arnold S. |last2=Cowling |first2=Benjamin J. |last3=Peiris |first3=J. S. Malik |title=Viral Infections of Humans |chapter=Coronaviruses |date=2014 |pages=199–223 |doi=10.1007/978-1-4899-7448-8_10 |pmc=7122465 |isbn=978-1-4899-7447-1 |quote=The other OC strains and B814 that could not be adapted to mouse brain resisted adaptation to cell culture as well; these distinct viruses have since been lost and may actually have been rediscovered recently }}</ref> Other human coronaviruses have since been identified, including [[Severe acute respiratory syndrome coronavirus|SARS-CoV]] in 2003, [[Human coronavirus NL63|HCoV NL63]] in 2003, [[Human coronavirus HKU1|HCoV HKU1]] in 2004, [[Middle East respiratory syndrome-related coronavirus|MERS-CoV]] in 2013, and [[SARS-CoV-2]] in 2019.<ref>{{cite journal | vauthors = Zhu N, Zhang D, Wang W, Li X, Yang B, Song J, Zhao X, Huang B, Shi W, Lu R, Niu P, Zhan F, Ma X, Wang D, Xu W, Wu G, Gao GF, Tan W | title = A Novel Coronavirus from Patients with Pneumonia in China, 2019 | journal = The New England Journal of Medicine | volume = 382 | issue = 8 | pages = 727–733 | date = February 2020 | pmid = 31978945 | pmc = 7092803 | doi = 10.1056/NEJMoa2001017 }}</ref> There have also been a large number of animal coronaviruses identified since the 1960s.''<ref name="groot">{{cite book |title=Virus Taxonomy |chapter=Coronaviridae |date=2012 |pages=806–828 |doi=10.1016/B978-0-12-384684-6.00068-9 |pmc=7149967 |isbn=978-0-12-384684-6 }}</ref>''

== Virology ==

=== Structure ===
[[File:Vaccines-08-00587-g002-A.png|thumb|right|Structure of a coronavirus]]

Coronaviruses are large, roughly spherical particles with unique surface projections.<ref>{{cite journal | vauthors = Goldsmith CS, Tatti KM, Ksiazek TG, Rollin PE, Comer JA, Lee WW, Rota PA, Bankamp B, Bellini WJ, Zaki SR | title = Ultrastructural characterization of SARS coronavirus | journal = Emerging Infectious Diseases | volume = 10 | issue = 2 | pages = 320–6 | date = February 2004 | pmid = 15030705 | pmc = 3322934 | doi = 10.3201/eid1002.030913 | quote = Virions acquired an envelope by budding into the cisternae and formed mostly spherical, sometimes pleomorphic, particles that averaged 78 nm in diameter (Figure 1A). }}</ref> Their size is highly variable with average diameters of 80&nbsp;to 120&nbsp;[[Nanometre|nm]]. Extreme sizes are known from 50 to 200&nbsp;nm in diameter.<ref name=":21">{{cite book |last1=Masters |first1=Paul S. |title=The Molecular Biology of Coronaviruses |series=Advances in Virus Research |date=2006 |volume=66 |pages=193–292 |doi=10.1016/S0065-3527(06)66005-3 |pmid=16877062 |pmc=7112330 |isbn=978-0-12-039869-0 }}</ref> The total [[molecular mass]] is on average 40,000&nbsp;[[Dalton (unit)|kDa]]. They are enclosed in an envelope embedded with a number of protein molecules.<ref name=":20">{{Cite journal| vauthors = Lalchhandama K |date=2020|title=The chronicles of coronaviruses: the electron microscope, the doughnut, and the spike |journal=Science Vision|language=en|volume=20|issue=2|pages=78–92|doi=10.33493/scivis.20.02.03|doi-access=free}}</ref> The lipid bilayer envelope, membrane proteins, and nucleocapsid protect the virus when it is outside the host cell.<ref>{{cite journal | vauthors = Neuman BW, Kiss G, Kunding AH, Bhella D, Baksh MF, Connelly S, Droese B, Klaus JP, Makino S, Sawicki SG, Siddell SG, Stamou DG, Wilson IA, Kuhn P, Buchmeier MJ | title = A structural analysis of M protein in coronavirus assembly and morphology | journal = Journal of Structural Biology | volume = 174 | issue = 1 | pages = 11–22 | date = April 2011 | pmid = 21130884 | pmc = 4486061 | doi = 10.1016/j.jsb.2010.11.021 | quote = See Figure 10. }}</ref>

The [[viral envelope]] is made up of a [[lipid bilayer]] in which the [[coronavirus membrane protein|membrane]] (M), [[coronavirus envelope protein|envelope]] (E) and [[spike protein|spike]] (S) [[Viral structural protein|structural proteins]] are anchored.<ref name="Lai_1997">{{cite book |last1=Lai |first1=Michael M.C. |last2=Cavanagh |first2=David |title=The Molecular Biology of Coronaviruses |series=Advances in Virus Research |date=1997 |volume=48 |pages=1–100 |doi=10.1016/S0065-3527(08)60286-9 |pmid=9233431 |pmc=7130985 |isbn=978-0-12-039848-5 }}</ref> The molar ratio of E:S:M in the lipid bilayer is approximately 1:20:300.<ref name="pmid1316677">{{cite journal |title=TGEV corona virus ORF4 encodes a membrane protein that is incorporated into virions |journal=Virology |date=1992 |volume=188 |issue=2 |pages=666–675 |doi=10.1016/0042-6822(92)90521-p |pmid=1316677 |pmc=7131960 | vauthors = Godet M, l'Haridon R, Vautherot J, Laude H }}</ref>  The E and M protein are the structural proteins that combined with the lipid bilayer to shape the viral envelope and maintain its size.<ref name="Fehr_2015" /> S proteins are needed for interaction with the host cells. But [[human coronavirus NL63]] is peculiar in that its M protein has the binding site for the host cell, and not its S protein.<ref>{{cite journal | vauthors = Naskalska A, Dabrowska A, Szczepanski A, Milewska A, Jasik KP, Pyrc K | title = Membrane Protein of Human Coronavirus NL63 Is Responsible for Interaction with the Adhesion Receptor | journal = Journal of Virology | volume = 93 | issue = 19 | date = October 2019 | article-number = e00355-19 | pmid = 31315999 | pmc = 6744225 | doi = 10.1128/JVI.00355-19 }}</ref> The diameter of the envelope is 85&nbsp;nm. The envelope of the virus in electron micrographs appears as a distinct pair of electron-dense shells (shells that are relatively opaque to the electron beam used to scan the virus particle).<ref>{{cite journal | vauthors = Neuman BW, Adair BD, Yoshioka C, Quispe JD, Orca G, Kuhn P, Milligan RA, Yeager M, Buchmeier MJ | title = Supramolecular architecture of severe acute respiratory syndrome coronavirus revealed by electron cryomicroscopy | journal = Journal of Virology | volume = 80 | issue = 16 | pages = 7918–28 | date = August 2006 | pmid = 16873249 | pmc = 1563832 | doi = 10.1128/JVI.00645-06 | quote = Particle diameters ranged from 50 to 150 nm, excluding the spikes, with mean particle diameters of 82 to 94 nm; Also See Figure{{nbsp}}1 for double shell. }}</ref><ref name="Fehr_2015" />

The [[coronavirus membrane protein|M protein]] is the main structural protein of the envelope that provides the overall shape and is a [[Bitopic protein|type III membrane protein]]. It consists of 218 to 263 [[amino acid]] residues and forms a layer 7.8&nbsp;nm thick.<ref name=":20" /> It has three domains, a short [[N-terminus|N-terminal]] [[ectodomain]], a triple-spanning [[transmembrane domain]], and a [[C-terminus|C-terminal]] [[Endoplasm|endodomain]]. The C-terminal domain forms a matrix-like lattice that adds to the extra-thickness of the envelope. Different species can have either ''N''- or ''O''-linked [[glycan]]s in their protein amino-terminal domain. The M protein is crucial during the assembly, [[budding]], envelope formation, and pathogenesis stages of the virus lifecycle.<ref>{{cite journal | vauthors = Schoeman D, Fielding BC | title = Coronavirus envelope protein: current knowledge | journal = Virology Journal | volume = 16 | issue = 1 | article-number = 69 | date = May 2019 | pmid = 31133031 | pmc = 6537279 | doi = 10.1186/s12985-019-1182-0 | doi-access = free }}</ref>

The [[coronavirus envelope protein|E proteins]] are minor structural proteins and highly variable in different species.<ref name=":21" /> There are only about 20 copies of the E protein molecule in a coronavirus particle.<ref name="pmid1316677" /> They are 8.4 to 12&nbsp;kDa in size and are composed of 76 to 109 amino acids.<ref name=":21" /> They are integral proteins (i.e. embedded in the lipid layer) and have two domains namely a transmembrane domain and an extramembrane C-terminal domain. They are almost fully α-helical, with a single α-helical transmembrane domain, and form pentameric (five-molecular) [[ion channel]]s in the lipid bilayer. They are responsible for virion assembly, [[Intracellular transport|intracellular trafficking]] and morphogenesis (budding).<ref name=":20" />

[[File:SARS-CoV MERS-CoV genome organization and S-protein domains.png|thumb|Diagram of the genome and functional domains of the S{{nbsp}}protein for SARS-CoV and MERS-CoV]]
The spikes are the most distinguishing feature of coronaviruses and are responsible for the corona- or halo-like surface. On average a coronavirus particle has 74 surface spikes.<ref>{{cite journal | vauthors = Neuman BW, Kiss G, Kunding AH, Bhella D, Baksh MF, Connelly S, Droese B, Klaus JP, Makino S, Sawicki SG, Siddell SG, Stamou DG, Wilson IA, Kuhn P, Buchmeier MJ | title = A structural analysis of M protein in coronavirus assembly and morphology | journal = Journal of Structural Biology | volume = 174 | issue = 1 | pages = 11–22 | date = April 2011 | pmid = 21130884 | pmc = 4486061 | doi = 10.1016/j.jsb.2010.11.021 }}</ref> Each [[Peplomer|spike]] is about 20&nbsp;nm long and is composed of a [[Protein trimer|trimer]] of the S{{nbsp}}protein. The S protein is in turn composed of an S1 and S2 [[Protein domain|subunit]]. The homotrimeric S{{nbsp}}protein is a [[Membrane fusion protein|class I fusion protein]] which mediates the [[Viral entry|receptor binding]] and [[Lipid bilayer fusion|membrane fusion]] between the virus and host cell. The S1 subunit forms the head of the spike and has the receptor-binding domain (RBD). The S2 subunit forms the stem which anchors the spike in the viral envelope and on protease activation enables fusion. The two subunits remain noncovalently linked as they are exposed on the viral surface until they attach to the host cell membrane.<ref name=":20" /> In a functionally active state, three S1 are attached to two S2 subunits. The subunit complex is split into individual subunits when the virus binds and fuses with the host cell under the action of [[proteases]] such as [[cathepsin]] family and [[TMPRSS2|transmembrane protease serine 2]] (TMPRSS2) of the host cell.<ref>{{cite journal | vauthors = J Alsaadi EA, Jones IM | title = Membrane binding proteins of coronaviruses | journal = Future Virology | volume = 14 | issue = 4 | pages = 275–286 | date = April 2019 | pmid = 32201500 | pmc = 7079996 | doi = 10.2217/fvl-2018-0144 }}</ref>

[[File:15010 2020 1486 Fig3 HTML.webp|thumb|After binding of the ACE2 receptor, SARS-CoV spike is activated and cleaved at the S1/S2 level.]]
S1 proteins are the most critical components in terms of infection. They are also the most variable components as they are responsible for host cell specificity. They possess two major domains named N-terminal domain (S1-NTD) and C-terminal domain (S1-CTD), both of which serve as the receptor-binding domains. The NTDs recognize and bind sugars on the surface of the host cell. An exception is the [[Murine coronavirus|MHV]] NTD that binds to a protein receptor [[carcinoembryonic antigen-related cell adhesion molecule 1]] (CEACAM1). S1-CTDs are responsible for recognizing different protein receptors such as [[angiotensin-converting enzyme 2]] (ACE2), [[aminopeptidase N]] (APN), and [[dipeptidyl peptidase 4]] (DPP4).<ref name=":20" />

A subset of coronaviruses (specifically the members of [[betacoronavirus]] [[Embecovirus|subgroup A]]) also has a shorter spike-like surface protein called [[hemagglutinin esterase]] (HE).<ref name="groot" /> The HE proteins occur as homodimers composed of about 400 amino acid residues and are 40 to 50&nbsp;kDa in size. They appear as tiny surface projections of 5 to 7&nbsp;nm long embedded in between the spikes. They help in the attachment to and detachment from the host cell.<ref>{{cite journal | vauthors = Zeng Q, Langereis MA, van Vliet AL, Huizinga EG, de Groot RJ | title = Structure of coronavirus hemagglutinin-esterase offers insight into corona and influenza virus evolution | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 105 | issue = 26 | pages = 9065–9 | date = July 2008 | pmid = 18550812 | pmc = 2449365 | doi = 10.1073/pnas.0800502105 | bibcode = 2008PNAS..105.9065Z | doi-access = free }}</ref>

Inside the envelope, there is the [[Capsid|nucleocapsid]], which is formed from multiple copies of the nucleocapsid (N) protein, which are bound to the positive-sense single-stranded [[RNA]] genome in a continuous [[bead]]s-on-a-string type conformation.<ref name="Fehr_2015">{{cite book | vauthors = Fehr AR, Perlman S | chapter = Coronaviruses: An Overview of Their Replication and Pathogenesis | title = Coronaviruses | series = Methods in Molecular Biology | volume = 1282 | pages = 1–23 | date = 2015 | pmid = 25720466 | pmc = 4369385 | doi = 10.1007/978-1-4939-2438-7_1 | publisher = Springer | isbn = 978-1-4939-2438-7 | quote = See section: Virion Structure. | veditors = Maier HJ, Bickerton E, Britton P }}</ref><ref>{{cite journal | vauthors = Chang CK, Hou MH, Chang CF, Hsiao CD, Huang TH | title = The SARS coronavirus nucleocapsid protein—forms and functions | journal = Antiviral Research | volume = 103 | pages = 39–50 | date = March 2014 | pmid = 24418573 | doi = 10.1016/j.antiviral.2013.12.009 | pmc = 7113676 | quote = See Figure 4c. | doi-access = free }}</ref> [[Coronavirus nucleocapsid protein|N protein]] is a [[phosphoprotein]] of 43 to 50&nbsp;kDa in size, and is divided into three conserved domains. The majority of the protein is made up of domains 1 and 2, which are typically rich in [[arginine]]s and [[lysine]]s. Domain 3 has a short carboxy terminal end and has a net negative charge due to excess of acidic over basic amino acid residues.<ref name=":21" />

=== Genome ===
{{See also|Severe acute respiratory syndrome–related coronavirus#Genome}}
[[File:SARS Coronavirus Genome Organization.png|thumb|SARS-CoV genome and proteins]]

Coronaviruses contain a [[Positive-sense single-stranded RNA virus|positive-sense, single-stranded RNA]] genome. The [[genome size]] for coronaviruses ranges from 26.4 to 31.7 [[Kilobase#Length measurements|kilobases]].<ref name=":1" /> The genome size is one of the largest among RNA viruses. The genome has a [[Five-prime cap|5′ methylated cap]] and a [[Polyadenylation|3′ polyadenylated tail]].<ref name="Fehr_2015" />

The genome organization for a coronavirus is [[Five prime untranslated region|5′-leader-UTR]]-replicase (ORF1ab)-spike (S)-envelope (E)-membrane (M)-nucleocapsid (N)-[[Three prime untranslated region|3′UTR]]-poly (A) tail. The [[open reading frame]]s 1a and 1b, which occupy the first two-thirds of the genome, encode the replicase polyprotein (pp1ab). The replicase polyprotein self cleaves to form 16 [[Viral nonstructural protein|nonstructural proteins]] (nsp1–nsp16).<ref name="Fehr_2015" />

The later reading frames encode the four major structural proteins: [[spike protein|spike]], [[coronavirus envelope protein|envelope]], [[coronavirus envelope protein|membrane]], and [[coronavirus nucleocapsid protein|nucleocapsid]].<ref>{{cite journal | vauthors = Snijder EJ, Bredenbeek PJ, Dobbe JC, Thiel V, Ziebuhr J, Poon LL, Guan Y, Rozanov M, Spaan WJ, Gorbalenya AE | title = Unique and conserved features of genome and proteome of SARS-coronavirus, an early split-off from the coronavirus group 2 lineage | journal = Journal of Molecular Biology | volume = 331 | issue = 5 | pages = 991–1004 | date = August 2003 | pmid = 12927536 | doi = 10.1016/S0022-2836(03)00865-9 | pmc = 7159028 | quote = See Figure 1. | doi-access = free }}</ref> Interspersed between these reading frames are the reading frames for the accessory proteins. The number of accessory proteins and their function is unique depending on the specific coronavirus.<ref name="Fehr_2015" />

=== Replication cycle ===

==== Cell entry ====
[[File:coronavirus replication.png|thumb|The life cycle of a coronavirus]]

Infection begins when the viral spike protein attaches to its complementary host cell receptor. After attachment, a [[protease]] of the host cell [[Proteolysis|cleaves]] and activates the receptor-attached spike protein. Depending on the host cell protease available, cleavage and activation allows the [[Viral entry|virus to enter]] the host cell by [[endocytosis]] or direct fusion of the viral envelope with the [[Lipid bilayer|host membrane]].<ref name=":6">{{cite journal | vauthors = Simmons G, Zmora P, Gierer S, Heurich A, Pöhlmann S | title = Proteolytic activation of the SARS-coronavirus spike protein: cutting enzymes at the cutting edge of antiviral research | journal = Antiviral Research | volume = 100 | issue = 3 | pages = 605–14 | date = December 2013 | pmid = 24121034 | pmc = 3889862 | doi = 10.1016/j.antiviral.2013.09.028 | quote = See Figure 2. }}</ref>

Coronaviruses can enter cells by either fusing to their lipid envelope with the cell membrane on the cell surface or by internalization via endocytosis.<ref>{{cite journal |last1=Szlachcic |first1=Wojciech J. |last2=Dabrowska |first2=Agnieszka |last3=Milewska |first3=Aleksandra |last4=Ziojla |first4=Natalia |last5=Blaszczyk |first5=Katarzyna |last6=Barreto-Duran |first6=Emilia |last7=Sanak |first7=Marek |last8=Surmiak |first8=Marcin |last9=Owczarek |first9=Katarzyna |last10=Grzanka |first10=Dariusz |last11=Durzynska |first11=Julia |last12=Pyrc |first12=Krzysztof |last13=Borowiak |first13=Malgorzata |title=SARS-CoV-2 infects an in vitro model of the human developing pancreas through endocytosis |journal=iScience |date=July 2022 |volume=25 |issue=7 |article-number=104594 |doi=10.1016/j.isci.2022.104594|pmid=35756892 |pmc=9212970 |bibcode=2022iSci...25j4594S }}</ref>

Insertion of a cleavage site can boost viral entry in different cell types by enabling promiscuous cleavage of the spike when contacting different proteases.<ref>{{cite journal |last1=Chan |first1=Yujia Alina |last2=Zhan |first2=Shing Hei |title=The Emergence of the Spike Furin Cleavage Site in SARS-CoV-2 |journal=Molecular Biology and Evolution |date=7 January 2022 |volume=39 |issue=1 |article-number=msab327 |doi=10.1093/molbev/msab327|pmid=34788836 |pmc=8689951 }}</ref>

==== Genome translation ====
On entry into the [[Host (biology)|host cell]], the virus particle is [[Uncoating|uncoated]], and its [[genome]] enters the [[Cytoplasm|cell cytoplasm]]. The coronavirus RNA genome has a 5′ methylated cap and a 3′ polyadenylated tail, which allows it to act like a [[messenger RNA]] and be directly translated by the host cell's [[ribosome]]s. The host ribosomes translate the initial overlapping [[Reading frame|open reading frames]] [[ORF1a]] and [[ORF1b]] of the virus genome into two large overlapping polyproteins, pp1a and pp1ab.<ref name="Fehr_2015" />

The larger polyprotein pp1ab is a result of a [[Ribosomal frameshift|-1 ribosomal frameshift]] caused by a [[slippery sequence]] (UUUAAAC) and a downstream [[Nucleic acid secondary structure|RNA pseudoknot]] at the end of open reading frame ORF1a.<ref name=":21"/> The ribosomal frameshift allows for the continuous translation of ORF1a followed by ORF1b.<ref name="Fehr_2015" />

The polyproteins have their own [[C30 Endopeptidase|proteases]],  [[Papain|PLpro]] (nsp3) and [[C30 Endopeptidase|3CLpro]] (nsp5), which cleave the polyproteins at different specific sites. The cleavage of polyprotein pp1ab yields 16 nonstructural proteins (nsp1 to nsp16). Product proteins include various replication  proteins such as [[RNA-dependent RNA polymerase]] ([[nsp12]]), [[RNA helicase]] (nsp13), and [[exoribonuclease]] (nsp14).<ref name="Fehr_2015" />

==== Replicase-transcriptase ====
[[File:Replication-transcription complex for Coronaviruses cropped.png|thumb|Replicase-transcriptase complex]]

A number of the nonstructural proteins coalesce to form a [[Protein complex|multi-protein]] replicase-transcriptase complex (RTC). The main replicase-transcriptase protein is the [[RNA-dependent RNA polymerase]] (RdRp). It is directly involved in the [[DNA replication|replication]] and [[Transcription (biology)|transcription]] of RNA from an RNA strand. The other nonstructural proteins in the complex assist in the replication and transcription process. The [[exoribonuclease]] nonstructural protein, for instance, provides extra fidelity to replication by providing a [[Proofreading (biology)|proofreading]] function which the RNA-dependent RNA polymerase lacks.<ref name="SextonSmith2016">{{cite journal | vauthors = Sexton NR, Smith EC, Blanc H, Vignuzzi M, Peersen OB, Denison MR | title = Homology-Based Identification of a Mutation in the Coronavirus RNA-Dependent RNA Polymerase That Confers Resistance to Multiple Mutagens | journal = Journal of Virology | volume = 90 | issue = 16 | pages = 7415–28 | date = August 2016 | pmid = 27279608 | pmc = 4984655 | doi = 10.1128/JVI.00080-16 | quote = Finally, these results, combined with those from previous work (33, 44), suggest that CoVs encode at least three proteins involved in fidelity (nsp12-RdRp, nsp14-ExoN, and nsp10), supporting the assembly of a multiprotein replicase-fidelity complex, as described previously (38). }}</ref>

''Replication'' – One of the main functions of the complex is to replicate the viral genome. RdRp directly mediates the [[DNA replication|synthesis]] of negative-sense genomic RNA from the positive-sense genomic RNA. This is followed by the replication of positive-sense genomic RNA from the negative-sense genomic RNA.<ref name="Fehr_2015" />

[[File:Transcription of nested mRNAs.jpg|thumb|Transcription of nested mRNAs]]
[[File:Nested subgenomic RNA.jpg|thumb|Nested set of subgenomic mRNAs]]

''Transcription'' – The other important function of the complex is to transcribe the viral genome. RdRp directly mediates the [[Transcription (biology)|synthesis]] of negative-sense subgenomic RNA molecules from the positive-sense genomic RNA. This process is followed by the transcription of these negative-sense subgenomic RNA molecules to their corresponding positive-sense [[Messenger RNA|mRNAs]].<ref name="Fehr_2015" /> The subgenomic mRNAs form a "[[Subgenomic mRNA|nested set]]" which have a common 5'-head and partially duplicate 3'-end.<ref name=":15">{{cite book |title=Viruses |chapter=Family Coronaviridae |date=2017 |pages=149–158 |doi=10.1016/B978-0-12-803109-4.00017-9 |isbn=978-0-12-803109-4 | vauthors = Payne S }}</ref>

''Recombination'' – The replicase-transcriptase complex is also capable of [[genetic recombination]] when at least two viral genomes are present in the same infected cell.<ref name=":15" />  RNA recombination appears to be a major driving force in determining genetic variability within a coronavirus species, the capability of a coronavirus species to jump from one host to another and, infrequently, in determining the emergence of novel coronaviruses.<ref name="Su2016">{{cite journal |vauthors=Su S, Wong G, Shi W, Liu J, Lai AC, Zhou J, Liu W, Bi Y, Gao GF | title = Epidemiology, Genetic Recombination, and Pathogenesis of Coronaviruses | journal = Trends in Microbiology | volume = 24 | issue = 6 | pages = 490–502 | date = June 2016 | pmid = 27012512 | pmc = 7125511 | doi = 10.1016/j.tim.2016.03.003 }}</ref>  The exact mechanism of recombination in coronaviruses is unclear, but likely involves template switching during genome replication.<ref name="Su2016" />

==== Assembly and release ====
The replicated positive-sense genomic RNA becomes the genome of the [[Viral shedding|progeny viruses]]. The mRNAs are gene transcripts of the last third of the virus genome after the initial overlapping reading frame. These mRNAs are translated by the host's ribosomes into the structural proteins and many accessory proteins.<ref name="Fehr_2015" /> RNA translation occurs inside the [[endoplasmic reticulum]]. The viral structural proteins S, E, and M move along the secretory pathway into the [[Vesicular-tubular cluster|Golgi intermediate compartment]]. There, the M{{nbsp}}proteins direct most protein-protein interactions required for the assembly of viruses following its binding to the [[nucleocapsid]]. Progeny viruses are then released from the host cell by [[exocytosis]] through secretory vesicles. Once released the viruses can infect other host cells.<ref name=":4">{{cite book|title=Coronaviruses|vauthors=Fehr AR, Perlman S|chapter=Coronaviruses: An Overview of Their Replication and Pathogenesis |date=2015|publisher=Springer|isbn=978-1-4939-2438-7|veditors=Maier HJ, Bickerton E, Britton P|series=Methods in Molecular Biology|volume=1282|pages=1–23|doi=10.1007/978-1-4939-2438-7_1|pmc=4369385|pmid=25720466|quote=See section: Coronavirus Life Cycle—Assembly and Release}}</ref>

=== Transmission ===
Infected carriers are able to [[Transmission (medicine)|shed viruses]] into the environment. The interaction of the coronavirus spike protein with its complementary [[Viral entry|cell receptor]] is central in determining the [[tissue tropism]], [[infectivity]], and [[Host tropism|species range]] of the released virus.<ref name=":21"/><ref>{{cite journal | vauthors = Cui J, Li F, Shi ZL | title = Origin and evolution of pathogenic coronaviruses | journal = Nature Reviews. Microbiology | volume = 17 | issue = 3 | pages = 181–92 | date = March 2019 | pmid = 30531947 | doi = 10.1038/s41579-018-0118-9 | pmc = 7097006 | quote = Different SARS-CoV strains isolated from several hosts vary in their binding affinities for human ACE2 and consequently in their infectivity of human cells 76, 78 (Fig. 6b) | doi-access = free }}</ref> Coronaviruses mainly target [[Epithelium|epithelial cells]].''<ref name="groot" />'' They are transmitted from one host to another host, depending on the coronavirus species, by either an [[Bioaerosol|aerosol]], [[fomite]], or [[Fecal–oral route|fecal-oral route]].<ref name=":12" />

Human coronaviruses infect the epithelial cells of the [[respiratory tract]], while animal coronaviruses generally infect the epithelial cells of the [[Gastrointestinal tract|digestive tract]].''<ref name="groot" />'' [[Severe acute respiratory syndrome–related coronavirus|SARS coronavirus]], for example, infects the human epithelial cells of the lungs via an aerosol route<ref name=":13" /> by binding to the [[angiotensin-converting enzyme 2]] (ACE2) receptor.<ref name="li">{{cite journal |title=Structure of SARS Coronavirus Spike Receptor-Binding Domain Complexed with Receptor |journal=Science |date=2005 |volume=309 |issue=5742 |pages=1864–1868 |doi=10.1126/science.1116480 |pmid=16166518 |bibcode=2005Sci...309.1864L | vauthors = Li F, Li W, Farzan M, Harrison SC }}</ref> [[Transmissible gastroenteritis virus|Transmissible gastroenteritis coronavirus]] (TGEV) infects the pig epithelial cells of the digestive tract via a fecal–oral route<ref name=":12" /> by binding to the [[alanine aminopeptidase]] (APN) receptor.<ref name="Fehr_2015" />

== Classification ==
{{For|a more detailed list of members|Coronaviridae}}
[[File:Phylogenetic tree of coronaviruses.jpg|thumb|Phylogenetic tree of coronaviruses]]

Coronaviruses form the subfamily ''Orthocoronavirinae,''<ref name="2017.012-015S"/><ref name="OrthocoronavirinaeICTV"/><ref name="FanZhao2019"/> which is one of two subfamilies in the family ''[[Coronaviridae]],'' order ''[[Nidovirales]],'' and realm ''[[Riboviria]].<ref name="groot" /><ref name=":5">{{Cite web|last=International Committee on Taxonomy of Viruses|date=24 August 2010|title=ICTV Master Species List 2009—v10|url=http://talk.ictvonline.org/files/ictv_documents/m/msl/1231/download.aspx|archive-url=https://archive.today/20130415045936/http://talk.ictvonline.org/files/ictv_documents/m/msl/1231/download.aspx|url-status=dead|archive-date=15 April 2013|format=xls}}</ref>'' They are divided into the four genera: ''Alphacoronavirus'', ''Betacoronavirus'', ''Gammacoronavirus'' and ''Deltacoronavirus''. Alphacoronaviruses and betacoronaviruses infect mammals, while gammacoronaviruses and deltacoronaviruses primarily infect birds.<ref>{{cite journal | vauthors = Wertheim JO, Chu DK, Peiris JS, Kosakovsky Pond SL, Poon LL | title = A case for the ancient origin of coronaviruses | journal = Journal of Virology | volume = 87 | issue = 12 | pages = 7039–45 | date = June 2013 | pmid = 23596293 | pmc = 3676139 | doi = 10.1128/JVI.03273-12 | bibcode = 2013JVir...87.7039W | quote = Alphacoronaviruses and betacoronaviruses are found exclusively in mammals, whereas gammacoronaviruses and deltacoronaviruses primarily infect birds. }}</ref>''<ref>{{Cite web|url=https://nextstrain.org/groups/blab/beta-cov|title= Nextstrain, phylogenetic tree of Beta-CoV |website=nextstrain.org}}</ref>''
* Genus: '''''[[Alphacoronavirus]]''''';<ref name=":12">{{cite book |last=Decaro|first=Nicola |title=The Springer Index of Viruses |chapter=Alphacoronavirus‡: Coronaviridae |date=2011 |pages=371–383|editor-last=Tidona|editor-first=Christian|publisher=Springer|language=en|doi=10.1007/978-0-387-95919-1_56|isbn=978-0-387-95919-1|pmc=7176201 |editor2-last=Darai|editor2-first=Gholamreza}}</ref>
** Species: ''[[Alphacoronavirus 1]]'' ([[Transmissible gastroenteritis virus|TGEV]], [[Feline coronavirus]], [[Canine coronavirus]]), ''[[Human coronavirus 229E]]'', ''[[Human coronavirus NL63]]'', ''[[Miniopterus bat coronavirus 1]]'', ''[[Miniopterus bat coronavirus HKU8]]'', ''[[Porcine epidemic diarrhea virus]]'', ''[[Rhinolophus bat coronavirus HKU2]]'', ''[[Scotophilus bat coronavirus 512]]''
* Genus '''''[[Betacoronavirus]]''''';<ref name=":13">{{cite book |last=Decaro|first=Nicola|title=The Springer Index of Viruses |chapter=Betacoronavirus‡: Coronaviridae |date=2011|pages=385–401|editor-last=Tidona|editor-first=Christian |editor2-last=Darai|editor2-first=Gholamreza |publisher=Springer |doi=10.1007/978-0-387-95919-1_57|isbn=978-0-387-95919-1|pmc=7176184}}</ref>
** Species: ''[[Betacoronavirus 1]]'' ([[Bovine coronavirus|''Bovine Coronavirus'']], ''[[Human coronavirus OC43]]''), ''[[Hedgehog coronavirus 1]],'' ''[[Human coronavirus HKU1]]'', ''[[Middle East respiratory syndrome-related coronavirus]],'' ''[[Murine coronavirus]]'', ''[[Pipistrellus bat coronavirus HKU5]]'', ''[[Rousettus bat coronavirus HKU9]]'', ''[[Severe acute respiratory syndrome–related coronavirus]]'' (''[[SARS-CoV-1]]'', ''[[SARS-CoV-2]]''), ''[[Tylonycteris bat coronavirus HKU4]]''
* Genus '''''[[Gammacoronavirus]]''''';<ref name=":11" />
** Species: ''[[Avian coronavirus]],'' ''[[Beluga whale coronavirus SW1]]''
* Genus '''''[[Deltacoronavirus (genus)|Deltacoronavirus]]'''''
** Species: ''[[Bulbul coronavirus HKU11]]'', [[Porcine coronavirus HKU15|''Porcine'' ''coronavirus HKU15'']]

== Origin ==
[[File:Animal origins of human coronaviruses.png|thumb|Origins of human coronaviruses with possible intermediate hosts]]
The [[most recent common ancestor]] (MRCA) of all coronaviruses is estimated to have existed as recently as 8000&nbsp;[[BCE]], although some models place the common ancestor as far back as 55&nbsp;million years or more, implying long term coevolution with bat and avian species.<ref name="Wertheim2013">{{cite journal | vauthors = Wertheim JO, Chu DK, Peiris JS, Kosakovsky Pond SL, Poon LL | title = A case for the ancient origin of coronaviruses | journal = Journal of Virology | volume = 87 | issue = 12 | pages = 7039–45 | date = June 2013 | pmid = 23596293 | pmc = 3676139 | doi = 10.1128/JVI.03273-12 | bibcode = 2013JVir...87.7039W }}</ref> The most recent common ancestor of the alphacoronavirus line has been placed at about 2400&nbsp;BCE, of the betacoronavirus line at 3300 BCE, of the gammacoronavirus line at 2800&nbsp;BCE, and the deltacoronavirus line at about 3000 BCE. Bats and birds, as [[warm-blooded]] flying vertebrates, are an ideal [[natural reservoir]] for the coronavirus gene pool (with [[Bat-borne virus|bats the reservoir]] for alphacoronaviruses and betacoronavirus{{snd}}and birds the reservoir for gammacoronaviruses and deltacoronaviruses). The large number and global range of bat and avian species that host viruses have enabled extensive evolution and dissemination of coronaviruses.<ref name="Woo2012">{{cite journal | vauthors = Woo PC, Lau SK, Lam CS, Lau CC, Tsang AK, Lau JH, Bai R, Teng JL, Tsang CC, Wang M, Zheng BJ, Chan KH, Yuen KY | title = Discovery of seven novel mammalian and avian coronaviruses in the genus deltacoronavirus supports bat coronaviruses as the gene source of alphacoronavirus and betacoronavirus and avian coronaviruses as the gene source of gammacoronavirus and deltacoronavirus | journal = Journal of Virology | volume = 86 | issue = 7 | pages = 3995–4008 | date = April 2012 | pmid = 22278237 | pmc = 3302495 | doi = 10.1128/JVI.06540-11 | bibcode = 2012JVir...86.3995W }}</ref> A number of 2021 studies found that the MRCA for Coronaviruses may have emerged around 21,000–25,000 years ago in East Asia, which is significantly earlier than most prior estimates.<ref name="ancient viral epidemic" /><ref name="21,000 years ago" />

Many human coronaviruses have their origin in bats.<ref name=":8" /> The human coronavirus NL63 shared a common ancestor with a bat coronavirus (ARCoV.2) between 1190 and 1449 CE.<ref name="Huynh2012">{{cite journal | vauthors = Huynh J, Li S, Yount B, Smith A, Sturges L, Olsen JC, Nagel J, Johnson JB, Agnihothram S, Gates JE, Frieman MB, Baric RS, Donaldson EF | title = Evidence supporting a zoonotic origin of human coronavirus strain NL63 | journal = Journal of Virology | volume = 86 | issue = 23 | pages = 12816–25 | date = December 2012 | pmid = 22993147 | pmc = 3497669 | doi = 10.1128/JVI.00906-12 | quote = If these predictions are correct, this observation suggests that HCoV-NL63 may have originated from bats between 1190 and 1449 CE. }}</ref> The human coronavirus 229E shared a common ancestor with a bat coronavirus (GhanaGrp1 Bt CoV) between 1686 and 1800&nbsp;CE.<ref>{{cite journal | vauthors = Pfefferle S, Oppong S, Drexler JF, Gloza-Rausch F, Ipsen A, Seebens A, Müller MA, Annan A, Vallo P, Adu-Sarkodie Y, Kruppa TF, Drosten C | title = Distant relatives of severe acute respiratory syndrome coronavirus and close relatives of human coronavirus 229E in bats, Ghana | journal = Emerging Infectious Diseases | volume = 15 | issue = 9 | pages = 1377–84 | date = September 2009 | pmid = 19788804 | pmc = 2819850 | doi = 10.3201/eid1509.090224 | bibcode = 2009EIDis..15.1377P | quote = The most recent common ancestor of hCoV-229E and GhanaBt-CoVGrp1 existed in ≈1686–1800 AD. }}</ref> More recently, [[alpaca]] coronavirus and human coronavirus 229E diverged sometime before 1960.<ref name="Crossley2012">{{cite journal | vauthors = Crossley BM, Mock RE, Callison SA, Hietala SK | title = Identification and characterization of a novel alpaca respiratory coronavirus most closely related to the human coronavirus 229E | journal = Viruses | volume = 4 | issue = 12 | pages = 3689–700 | date = December 2012 | pmid = 23235471 | pmc = 3528286 | doi = 10.3390/v4123689 | doi-access = free }}</ref> MERS-CoV emerged in humans from bats through the intermediate host of camels.<ref>{{cite journal | vauthors = Forni D, Cagliani R, Clerici M, Sironi M | title = Molecular Evolution of Human Coronavirus Genomes | journal = Trends in Microbiology | volume = 25 | issue = 1 | pages = 35–48 | date = January 2017 | pmid = 27743750 | pmc = 7111218 | doi = 10.1016/j.tim.2016.09.001 | bibcode = 2017TrMic..25...35F }}</ref> MERS-CoV, although related to several bat coronavirus species, appears to have diverged from these several centuries ago.<ref name="Lau2013">{{cite journal | vauthors = Lau SK, Li KS, Tsang AK, Lam CS, Ahmed S, Chen H, Chan KH, Woo PC, Yuen KY | title = Genetic characterization of Betacoronavirus lineage C viruses in bats reveals marked sequence divergence in the spike protein of pipistrellus bat coronavirus HKU5 in Japanese pipistrelle: implications for the origin of the novel Middle East respiratory syndrome coronavirus | journal = Journal of Virology | volume = 87 | issue = 15 | pages = 8638–50 | date = August 2013 | pmid = 23720729 | pmc = 3719811 | doi = 10.1128/JVI.01055-13 }}</ref> The most closely related bat coronavirus and SARS-CoV diverged in 1986.<ref name="Vijaykrishna2007">{{cite journal | vauthors = Vijaykrishna D, Smith GJ, Zhang JX, Peiris JS, Chen H, Guan Y | title = Evolutionary insights into the ecology of coronaviruses | journal = Journal of Virology | volume = 81 | issue = 8 | pages = 4012–20 | date = April 2007 | pmid = 17267506 | pmc = 1866124 | doi = 10.1128/jvi.02605-06 }}</ref> The ancestors of SARS-CoV first infected leaf-nose bats of the genus ''[[Hipposideridae]]''; subsequently, they spread to horseshoe bats in the species ''[[Rhinolophidae]]'', then to [[Asian palm civet]]s, and finally to humans.<ref>{{cite journal | vauthors = Gouilh MA, Puechmaille SJ, Gonzalez JP, Teeling E, Kittayapong P, Manuguerra JC | title = SARS-Coronavirus ancestor's foot-prints in South-East Asian bat colonies and the refuge theory | journal = Infection, Genetics and Evolution | volume = 11 | issue = 7 | pages = 1690–702 | date = October 2011 | pmid = 21763784 | doi = 10.1016/j.meegid.2011.06.021 | pmc = 7106191| bibcode = 2011InfGE..11.1690G }}</ref><ref name="pmid18258002">{{cite journal | vauthors = Cui J, Han N, Streicker D, Li G, Tang X, Shi Z, Hu Z, Zhao G, Fontanet A, Guan Y, Wang L, Jones G, Field HE, Daszak P, Zhang S | title = Evolutionary relationships between bat coronaviruses and their hosts | journal = Emerging Infectious Diseases | volume = 13 | issue = 10 | pages = 1526–32 | date = October 2007 | pmid = 18258002 | pmc = 2851503 | doi = 10.3201/eid1310.070448 }}</ref>

Unlike other betacoronaviruses, [[bovine coronavirus]] of the species ''[[Betacoronavirus 1]]'' and subgenus ''[[Embecovirus]]'' is thought to have originated in [[rodent]]s and not in bats.<ref name=":8">{{cite journal | vauthors = Forni D, Cagliani R, Clerici M, Sironi M | title = Molecular Evolution of Human Coronavirus Genomes | journal = Trends in Microbiology | volume = 25 | issue = 1 | pages = 35–48 | date = January 2017 | pmid = 27743750 | pmc = 7111218 | doi = 10.1016/j.tim.2016.09.001 | bibcode = 2017TrMic..25...35F | quote = Specifically, all HCoVs are thought to have a bat origin, with the exception of lineage A beta-CoVs, which may have reservoirs in rodents [2]. }}</ref><ref>{{cite journal | vauthors = Lau SK, Woo PC, Li KS, Tsang AK, Fan RY, Luk HK, Cai JP, Chan KH, Zheng BJ, Wang M, Yuen KY | title = Discovery of a novel coronavirus, China Rattus coronavirus HKU24, from Norway rats supports the murine origin of Betacoronavirus 1 and has implications for the ancestor of Betacoronavirus lineage A | journal = Journal of Virology | volume = 89 | issue = 6 | pages = 3076–92 | date = March 2015 | pmid = 25552712 | pmc = 4337523 | doi = 10.1128/JVI.02420-14 }}</ref> In the 1790s, equine coronavirus diverged from the bovine coronavirus after a [[Cross-species transmission|cross-species jump]].<ref name=":7">{{cite journal | vauthors = Bidokhti MR, Tråvén M, Krishna NK, Munir M, Belák S, Alenius S, Cortey M | title = Evolutionary dynamics of bovine coronaviruses: natural selection pattern of the spike gene implies adaptive evolution of the strains | journal = The Journal of General Virology | volume = 94 | issue = Pt 9 | pages = 2036–2049 | date = September 2013 | pmid = 23804565 | doi = 10.1099/vir.0.054940-0 | quote = See Table 1 | doi-access = free }}</ref> Later in the 1890s, human coronavirus OC43 diverged from bovine coronavirus after another cross-species spillover event.<ref name="Vijgen2005">{{cite journal | vauthors = Vijgen L, Keyaerts E, Moës E, Thoelen I, Wollants E, Lemey P, Vandamme AM, Van Ranst M | title = Complete genomic sequence of human coronavirus OC43: molecular clock analysis suggests a relatively recent zoonotic coronavirus transmission event | journal = Journal of Virology | volume = 79 | issue = 3 | pages = 1595–604 | date = February 2005 | pmid = 15650185 | pmc = 544107 | doi = 10.1128/jvi.79.3.1595-1604.2005 }}</ref><ref name=":7" /> It is speculated that the [[1889–1890 flu pandemic|flu pandemic of 1890]] may have been caused by this spillover event, and not by the [[Orthomyxoviridae|influenza virus]], because of the related timing, neurological symptoms, and unknown causative agent of the pandemic.<ref>{{cite journal | vauthors = Vijgen L, Keyaerts E, Moës E, Thoelen I, Wollants E, Lemey P, Vandamme AM, Van Ranst M | title = Complete genomic sequence of human coronavirus OC43: molecular clock analysis suggests a relatively recent zoonotic coronavirus transmission event | journal = Journal of Virology | volume = 79 | issue = 3 | pages = 1595–604 | date = February 2005 | pmid = 15650185 | pmc = 544107 | doi = 10.1128/JVI.79.3.1595-1604.2005 | quote = However, it is tempting to speculate about an alternative hypothesis, that the 1889-1890 pandemic may have been the result of interspecies transmission of bovine coronaviruses to humans, resulting in the subsequent emergence of HCoV-OC43. }}</ref> Besides causing respiratory infections, human coronavirus OC43 is also suspected of playing a role in [[Demyelinating disease|neurological diseases]].<ref name="pmid29551135"/> In the 1950s, the human coronavirus OC43 began to diverge into its present [[genotype]]s.<ref name="Lau2011">{{cite journal | vauthors = Lau SK, Lee P, Tsang AK, Yip CC, Tse H, Lee RA, So LY, Lau YL, Chan KH, Woo PC, Yuen KY | title = Molecular epidemiology of human coronavirus OC43 reveals evolution of different genotypes over time and recent emergence of a novel genotype due to natural recombination | journal = Journal of Virology | volume = 85 | issue = 21 | pages = 11325–37 | date = November 2011 | pmid = 21849456 | pmc = 3194943 | doi = 10.1128/JVI.05512-11 }}</ref> Phylogenetically, mouse hepatitis virus (''[[Murine coronavirus]]''), which infects the mouse's liver and [[Central nervous system viral disease|central nervous system]],<ref>{{cite journal | vauthors = Schaumburg CS, Held KS, Lane TE | title = Mouse hepatitis virus infection of the CNS: a model for defense, disease, and repair | journal = Frontiers in Bioscience | volume = 13 | pages = 4393–406 | date = May 2008 | issue = 13 | pmid = 18508518 | pmc = 5025298 | doi = 10.2741/3012 }}</ref> is related to human coronavirus OC43 and bovine coronavirus. Human coronavirus HKU1, like the aforementioned viruses, also has its origins in rodents.<ref name=":8" />

== Infection in humans ==
<!--Section linked to from [[Common cold]]-->[[File:Fphar-11-00937-g001.jpg|thumb|Transmission and life-cycle of SARS-CoV-2 causing [[Coronavirus disease 2019|COVID-19]]]]
Coronaviruses vary significantly in risk factor. Some can kill more than 30% of those infected, such as [[Middle East respiratory syndrome-related coronavirus|MERS-CoV]], and some are relatively harmless, such as the common cold.<ref name="Fehr_2015" /> Coronaviruses can cause colds with major symptoms, such as fever, and a [[sore throat]] from swollen [[adenoid]]s.<ref>{{cite journal | vauthors = Liu P, Shi L, Zhang W, He J, Liu C, Zhao C, Kong SK, Loo JF, Gu D, Hu L | title = Prevalence and genetic diversity analysis of human coronaviruses among cross-border children | language = En | journal = Virology Journal | volume = 14 | issue = 1 | article-number = 230 | date = November 2017 | pmid = 29166910 | pmc = 5700739 | doi = 10.1186/s12985-017-0896-0 | doi-access = free }}</ref> Coronaviruses can cause [[pneumonia]] (either direct [[viral pneumonia]] or secondary [[bacterial pneumonia]]) and [[bronchitis]] (either direct viral bronchitis or secondary bacterial bronchitis).<ref name="pmid19199189">{{cite journal |title=Healthcare-Associated Atypical Pneumonia |journal=Seminars in Respiratory and Critical Care Medicine |date=2009 |volume=30 |issue=1 |pages=067–085 |doi=10.1055/s-0028-1119811 |pmid=19199189 | vauthors = Forgie S, Marrie T }}</ref> The human coronavirus discovered in 2003, [[SARS coronavirus|SARS-CoV]], which causes [[severe acute respiratory syndrome]] (SARS), has a unique pathogenesis because it causes both [[upper respiratory tract infection|upper]] and [[lower respiratory tract infection]]s.<ref name="pmid19199189" />

Six species of human coronaviruses are known, with one species subdivided into two different strains, making seven strains of human coronaviruses altogether.

[[File:Journal.pmed.0020240.g001.tif|thumb|Seasonal distribution of HCoV-NL63 in Germany shows a preferential detection from November to March.]]

Four human coronaviruses produce symptoms that are generally mild, even though it is contended they might have been more aggressive in the past:<ref>{{Cite journal |title=An uncommon cold |journal=New Scientist |date=2020 |volume=246 |issue=3280 |pages=32–35 |doi=10.1016/S0262-4079(20)30862-9 |pmid=32501321 |bibcode=2020NewSc.246...32K | vauthors = King A |pmc=7252012 }}</ref>
# [[Human coronavirus OC43]] (HCoV-OC43), [[Betacoronavirus|β-CoV]]
# [[Human coronavirus HKU1]] (HCoV-HKU1), β-CoV
# [[Human coronavirus 229E]] (HCoV-229E), [[Alphacoronavirus|α-CoV]]
# [[Human coronavirus NL63]] (HCoV-NL63), α-CoV–

Three human coronaviruses produce potentially severe symptoms:
# [[Severe acute respiratory syndrome coronavirus]] (SARS-CoV), β-CoV (identified in 2003) 
# [[Middle East respiratory syndrome-related coronavirus]] (MERS-CoV), β-CoV (identified in 2012)
# [[Severe acute respiratory syndrome coronavirus 2]] (SARS-CoV-2), β-CoV (identified in 2019)

These cause the diseases commonly called [[Severe acute respiratory syndrome|SARS]], [[Middle East respiratory syndrome|MERS]], and [[COVID-19]] respectively.

=== Common cold ===
{{Main|Common cold}}

Although the [[common cold]] is usually caused by [[rhinovirus]]es,<ref name="CecilGoldman2012">{{cite book|first1=Russell La Fayette|last1=Cecil|first2=Lee|last2=Goldman|first3=Andrew I.|last3=Schafer|title=Goldman's Cecil Medicine, Expert Consult Premium Edition|url=https://books.google.com/books?id=Qd-vvNh0ee0C&pg=PA2103|pages=2103–|year=2012|archive-url=https://web.archive.org/web/20160504202334/https://books.google.com/books?id=Qd-vvNh0ee0C&pg=PA2103|edition=24|publisher=Elsevier Health Sciences|isbn=978-1-4377-1604-7|archive-date=4 May 2016|url-status=live}}</ref> in about 15% of cases the cause is a coronavirus.<ref>{{cite book|last=Pelczar|url=https://books.google.com/books?id=xnClBCuo71IC&pg=PA656|title=Microbiology: Application Based Approach|year=2010|isbn=978-0-07-015147-5|page=656| publisher=McGraw-Hill Education (India) Pvt Limited |archive-url=https://web.archive.org/web/20160516134615/https://books.google.com/books?id=xnClBCuo71IC&pg=PA656|archive-date=16 May 2016|url-status=live}}</ref> The human coronaviruses HCoV-OC43, HCoV-HKU1, HCoV-229E, and HCoV-NL63 continually circulate in the human population in adults and children worldwide and produce the generally mild symptoms of the common cold.<ref name="pmid29551135">{{cite book |last1=Corman |first1=Victor M. |last2=Muth |first2=Doreen |last3=Niemeyer |first3=Daniela |last4=Drosten |first4=Christian |title=Hosts and Sources of Endemic Human Coronaviruses |series=Advances in Virus Research |date=2018 |volume=100 |pages=163–188 |doi=10.1016/bs.aivir.2018.01.001 |pmid=29551135 |pmc=7112090 |isbn=978-0-12-815201-0 }}</ref> The four mild coronaviruses have a seasonal incidence occurring in the winter months in [[temperate climate]]s.<ref>{{cite journal | vauthors = Charlton CL, Babady E, Ginocchio CC, Hatchette TF, Jerris RC, Li Y, Loeffelholz M, McCarter YS, Miller MB, Novak-Weekley S, Schuetz AN, Tang YW, Widen R, Drews SJ | title = Practical Guidance for Clinical Microbiology Laboratories: Viruses Causing Acute Respiratory Tract Infections | journal = Clinical Microbiology Reviews | volume = 32 | issue = 1 | date = January 2019 | article-number = e00042-18 | pmid = 30541871 | doi = 10.1128/CMR.00042-18 | pmc = 6302358 | quote = See Figure 1. }}</ref><ref>{{cite journal | vauthors = Monto AS, DeJonge P, Callear AP, Bazzi LA, Capriola S, Malosh RE, Martin ET, Petrie JG | title = Coronavirus occurrence and transmission over 8 years in the HIVE cohort of households in Michigan | journal = The Journal of Infectious Diseases | pages = 9–16 | date = April 2020 | volume = 222 | pmid = 32246136 | doi = 10.1093/infdis/jiaa161 | pmc = 7184402 }}</ref>  There is no preponderance in any season in [[tropical climate]]s.<ref name="Abdul-Rasool_2010">{{cite journal | vauthors = Abdul-Rasool S, Fielding BC | title = Understanding Human Coronavirus HCoV-NL63 | journal = The Open Virology Journal | volume = 4 | pages = 76–84 | date = May 2010 | pmid = 20700397 | pmc = 2918871 | doi =  10.2174/1874357901004010076  | doi-broken-date = 23 December 2025 |doi-access=free}}</ref>

{{anchor|Outbreaks}}

=== Severe acute respiratory syndrome (SARS) ===

{{Main|SARS}}
{{Coronavirus characteristics comparison}}
In 2003, following the outbreak of severe acute respiratory syndrome (SARS) which had begun the prior year in Asia, and secondary cases elsewhere in the world, the [[World Health Organization]] (WHO) issued a press release stating that a novel coronavirus identified by several laboratories was the causative agent for SARS. The virus was officially named the SARS coronavirus (SARS-CoV). More than 8,000 people from 29 countries and territories were infected, and at least 774 died.<ref>{{Cite web|last=Pasley|first=James|title=How SARS terrified the world in 2003, infecting more than 8,000 people and killing 774|url=https://www.businessinsider.com/deadly-sars-virus-history-2003-in-photos-2020-2|access-date=8 November 2020|website=Business Insider}}</ref><ref name="li" />

=== Middle East respiratory syndrome (MERS) ===
{{Main|MERS}}

In September 2012, a new type of coronavirus was identified, initially called Novel Coronavirus 2012, and now officially named Middle East respiratory syndrome coronavirus (MERS-CoV).<ref name="NPR">{{Cite news |url=https://www.npr.org/blogs/health/2012/09/25/161770135/scientists-go-deep-on-genes-of-sars-like-virus |title=Scientists Go Deep On Genes Of SARS-Like Virus |last=Doucleef |first=Michaeleen |date=26 September 2012 |agency=Associated Press |access-date=27 September 2012 |archive-url=https://web.archive.org/web/20120927043755/http://www.npr.org/blogs/health/2012/09/25/161770135/scientists-go-deep-on-genes-of-sars-like-virus |archive-date=27 September 2012 |url-status=live}}</ref><ref>{{Cite news |url=http://thechart.blogs.cnn.com/2012/09/24/new-sars-like-virus-poses-medical-mystery/?hpt=he_c2 |title=New SARS-like virus poses medical mystery |last=Falco |first=Miriam |date=24 September 2012 |work=CNN Health |access-date=16 March 2013 |archive-url=https://web.archive.org/web/20131101042029/http://thechart.blogs.cnn.com/2012/09/24/new-sars-like-virus-poses-medical-mystery/?hpt=he_c2 |archive-date=1 November 2013 |url-status=dead}}</ref> The World Health Organization issued a global alert soon after.<ref>{{Cite news |url=http://www.aljazeera.com/news/middleeast/2012/09/2012924182013530585.html |title=New SARS-like virus found in Middle East |date=24 September 2012 |work=Al-Jazeera |access-date=16 March 2013 |archive-url=https://web.archive.org/web/20130309203607/http://www.aljazeera.com/news/middleeast/2012/09/2012924182013530585.html |archive-date=9 March 2013 |url-status=live}}</ref> The WHO update on 28&nbsp;September 2012 said the virus did not seem to pass easily from person to person.<ref name="Reuters2012">{{Cite news |url=https://www.reuters.com/article/us-virus-who-idUSBRE88R0F220120928 |title=New virus not spreading easily between people: WHO |last=Kelland |first=Kate |date=28 September 2012 |work=Reuters |access-date=16 March 2013 |archive-url=https://web.archive.org/web/20121124005044/http://www.reuters.com/article/2012/09/28/us-virus-who-idUSBRE88R0F220120928 |archive-date=24 November 2012 |url-status=live}}</ref> However, on 12&nbsp;May 2013, a case of [[human-to-human transmission]] in France was confirmed by the French Ministry of Social Affairs and Health.<ref name="may12">[http://www.social-sante.gouv.fr/actualite-presse,42/communiques,2322/nouveau-coronavirus-point-de,15820.html ''Nouveau coronavirus—Point de situation : Un nouveau cas d'infection confirmé''] {{Webarchive|url=https://web.archive.org/web/20130608140519/http://www.social-sante.gouv.fr/actualite-presse,42/communiques,2322/nouveau-coronavirus-point-de,15820.html|date=8 June 2013}} ''(Novel coronavirus—Status report: A new case of confirmed infection)'' 12 May 2013, social-sante.gouv.fr</ref> In addition, cases of human-to-human transmission were reported by the Ministry of Health in [[Tunisia]]. Two confirmed cases involved people who seemed to have caught the disease from their late father, who became ill after a visit to Qatar and Saudi Arabia. Despite this, it appears the virus had trouble spreading from human to human, as most individuals who are infected do not transmit the virus.<ref>{{Cite web |url=https://www.cdc.gov/coronavirus/mers/about/transmission.html |title=MERS Transmission |date=2 August 2019 |website=Centers for Disease Control and Prevention (CDC)|access-date=10 December 2019 |archive-url=https://web.archive.org/web/20191207073553/https://www.cdc.gov/coronavirus/mers/about/transmission.html |archive-date=7 December 2019 |url-status=live}}</ref> By 30&nbsp;October 2013, there were 124 cases and 52 deaths in Saudi Arabia.<ref name="may22">{{Cite web |url=https://www.who.int/csr/don/2013_05_22_ncov/en/index.html |title=Novel coronavirus infection|date=22 May 2013 |publisher=World Health Association |access-date=23 May 2013 |archive-url=https://web.archive.org/web/20130607163823/http://www.who.int/csr/don/2013_05_22_ncov/en/index.html |archive-date=7 June 2013 |url-status=dead}}</ref>

After the Dutch [[Erasmus MC|Erasmus Medical Centre]] sequenced the virus, the virus was given a new name, Human Coronavirus–Erasmus Medical Centre (HCoV-EMC). The final name for the virus is Middle East respiratory syndrome coronavirus (MERS-CoV). The only U.S. cases (both survived) were recorded in May 2014.<ref>{{Cite web |url=https://www.cdc.gov/coronavirus/mers/us.html |title=MERS in the U.S. |date=2 August 2019 |website=Center for Disease Control |access-date=10 December 2019 |archive-url=https://web.archive.org/web/20191215030453/https://www.cdc.gov/coronavirus/mers/US.html |archive-date=15 December 2019 |url-status=live}}</ref>

In May 2015, an outbreak of MERS-CoV occurred in the [[Republic of Korea]], when a man who had traveled to the Middle East, visited four hospitals in the Seoul area to treat his illness. This caused one of the largest outbreaks of MERS-CoV outside the Middle East.<ref>{{Cite news |url=https://www.nytimes.com/2015/06/09/world/asia/mers-viruss-path-one-man-many-south-korean-hospitals.html |title=MERS Virus's Path: One Man, Many South Korean Hospitals |last=Sang-Hun |first=Choe |date=8 June 2015 |work=The New York Times |access-date=1 March 2017 |archive-url=https://web.archive.org/web/20170715170528/https://www.nytimes.com/2015/06/09/world/asia/mers-viruss-path-one-man-many-south-korean-hospitals.html |archive-date=15 July 2017 |url-status=live}}</ref> As of December 2019, 2,468 cases of MERS-CoV infection had been confirmed by laboratory tests, 851 of which were fatal, a [[mortality rate]] of approximately 34.5%.<ref>{{Cite web |url=https://www.who.int/emergencies/mers-cov/en/ |title=Middle East respiratory syndrome coronavirus (MERS-CoV) |website=WHO |access-date=10 December 2019 |archive-url=https://web.archive.org/web/20191018010957/https://www.who.int/emergencies/mers-cov/en/ |archive-date=18 October 2019 |url-status=live}}</ref>

=== Coronavirus disease 2019 (COVID-19) ===
{{Main|COVID-19}}

In December 2019, a pneumonia outbreak was reported in [[Wuhan]], China.<ref name="NYT-20200129">{{cite news |author=The Editorial Board |title=Is the World Ready for the Coronavirus?—Distrust in science and institutions could be a major problem if the outbreak worsens|url=https://www.nytimes.com/2020/01/29/opinion/coronavirus-outbreak.html |date=29 January 2020 |work=[[The New York Times]] |access-date=30 January 2020}}</ref> On 31 December 2019, the outbreak was traced to a novel strain of coronavirus,<ref name="WHO9Jan2020">{{Cite web |url=https://www.who.int/china/news/detail/09-01-2020-who-statement-regarding-cluster-of-pneumonia-cases-in-wuhan-china |title=WHO Statement Regarding Cluster of Pneumonia Cases in Wuhan, China |date=9 January 2020 |website=www.who.int |language=en |url-status=live |access-date=10 January 2020 |archive-url=https://web.archive.org/web/20200114133102/https://www.who.int/china/news/detail/09-01-2020-who-statement-regarding-cluster-of-pneumonia-cases-in-wuhan-china |archive-date=14 January 2020}}</ref> which was given the interim name 2019-nCoV by the World Health Organization,<ref name="WHO20200110">{{cite report |title=Laboratory testing of human suspected cases of novel coronavirus (nCoV) infection: interim guidance, 10 January 2020 |date=10 January 2020 |publisher=World Health Organization |hdl=10665/330374 |hdl-access=free }}</ref><ref name="CDC20200113">{{Cite web|url=https://www.cdc.gov/coronavirus/2019-ncov/index.html|title=Novel Coronavirus 2019, Wuhan, China |date=23 January 2020|website=www.cdc.gov (CDC)|access-date=23 January 2020|archive-url=https://web.archive.org/web/20200120144040/https://www.cdc.gov/coronavirus/2019-ncov/index.html|archive-date=20 January 2020|url-status=live}}</ref><ref>{{Cite web |url=https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection.html |title=2019 Novel Coronavirus infection (Wuhan, China): Outbreak update |website=Canada.ca|date=21 January 2020}}</ref> later renamed [[SARS-CoV-2]] by the [[International Committee on Taxonomy of Viruses]].

As of {{Cases in the COVID-19 pandemic|date|editlink=|ref=no}}, there were at least {{Cases in the COVID-19 pandemic|deaths|editlink=|ref=}} [[COVID-19 pandemic deaths|confirmed deaths]] and more than {{Cases in the COVID-19 pandemic|confirmed|editlink=|ref=}} [[COVID-19 pandemic cases|confirmed cases]] in the [[COVID-19 pandemic]]. The Wuhan strain has been identified as a new strain of [[Betacoronavirus]] from group 2B with approximately 70% genetic similarity to the SARS-CoV.<ref>{{cite journal | vauthors = Hui DS, I Azhar E, Madani TA, Ntoumi F, Kock R, Dar O, Ippolito G, Mchugh TD, Memish ZA, Drosten C, Zumla A, Petersen E | title = The continuing 2019-nCoV epidemic threat of novel coronaviruses to global health—The latest 2019 novel coronavirus outbreak in Wuhan, China | journal = International Journal of Infectious Diseases | volume = 91 | pages = 264–66 | date = February 2020 | pmid = 31953166 | doi = 10.1016/j.ijid.2020.01.009 | pmc = 7128332 | author-link10 = Christian Drosten | doi-access = free }}</ref> The virus has a 96% similarity to a bat coronavirus, so it is widely suspected to originate from bats as well.<ref name=":0">{{Cite web|url=https://www.science.org/content/article/wuhan-seafood-market-may-not-be-source-novel-virus-spreading-globally|title=Wuhan seafood market may not be source of novel virus spreading globally|last=Cohen|first=Jon |date=26 January 2020|website=[[Science (journal)|ScienceMag]] American Association for the Advancement of Science. (AAAS)|language=en|url-status=live|archive-url=https://archive.today/20200127063253/https://www.sciencemag.org/news/2020/01/wuhan-seafood-market-may-not-be-source-novel-virus-spreading-globally|archive-date=27 January 2020|access-date=29 January 2020}}</ref><ref>{{Cite web|url=https://www.popsci.com/story/health/wuhan-coronavirus-china-wet-market-wild-animal/|title=We're still not sure where the COVID-19 really came from|last=Eschner|first=Kat|date=28 January 2020|website=[[Popular Science]]|language=en|url-status=live|archive-url=https://archive.today/20200130003350/https://www.popsci.com/story/health/wuhan-coronavirus-china-wet-market-wild-animal/|archive-date=30 January 2020|access-date=30 January 2020}}</ref>

=== Coronavirus HuPn-2018 ===
{{Main|Canine coronavirus HuPn-2018}}

During a surveillance study of archived samples of Malaysian viral pneumonia patients, virologists identified a strain of [[canine coronavirus]] which has infected humans in 2018.

== Infection in animals ==
Coronaviruses have been recognized as causing pathological conditions in [[veterinary medicine]] since the 1930s.<ref name=":3" />  They infect a range of animals including swine, cattle, horses, camels, cats, dogs, rodents, birds and bats.<ref name=":14">{{cite book |title=Fenner's Veterinary Virology |chapter=Coronaviridae |date=2017 |pages=435–461 |doi=10.1016/B978-0-12-800946-8.00024-6 |pmc=7149743 |isbn=978-0-12-800946-8 }}</ref>  The majority of animal related coronaviruses infect the [[Gastrointestinal tract|intestinal tract]] and are transmitted by a fecal-oral route.<ref>{{cite book | vauthors = Murphy FA, Gibbs EP, Horzinek MC, Studdart MJ |title=Veterinary Virology |publisher=Academic Press |location=Boston |year=1999|pages=495–508 |isbn=978-0-12-511340-3}}</ref> Significant research efforts have been focused on elucidating the [[viral pathogenesis]] of these animal coronaviruses, especially by [[virologist]]s interested in veterinary and [[zoonotic]] diseases.<ref name="pmid20627412">{{cite journal|vauthors=Tirotta E, Carbajal KS, Schaumburg CS, Whitman L, Lane TE|date=July 2010|title=Cell replacement therapies to promote remyelination in a viral model of demyelination|journal=Journal of Neuroimmunology|volume=224|issue=1–2|pages=101–07|doi=10.1016/j.jneuroim.2010.05.013|pmc=2919340|pmid=20627412}}</ref>

=== Farm animals ===
Coronaviruses infect domesticated birds.<ref name=":16">{{Cite web|title=Merck Veterinary Manual|url=https://www.merckvetmanual.com/|access-date=8 June 2020|website=Merck Veterinary Manual|language=en-US}}</ref> [[Infectious bronchitis virus]] (IBV), a type of coronavirus, causes [[avian infectious bronchitis]].<ref name="pmid25954763" /> The virus is of concern to the [[Poultry farming|poultry industry]] because of the high mortality from infection, its rapid spread, and its effect on production.<ref name=":14" /> The virus affects both meat production and egg production and causes substantial economic loss.<ref name="Cavanagh 2007">{{cite journal|last1=Cavanagh|first1=D|date=2007|title=Coronavirus avian infectious bronchitis virus|journal=Veterinary Research|volume=38|issue=2|pages=281–97|doi=10.1051/vetres:2006055|pmid=17296157|doi-access=free}}</ref> In chickens, infectious bronchitis virus targets not only the respiratory tract but also the [[urogenital tract]]. The virus can spread to different organs throughout the chicken.<ref name="pmid25954763">{{cite journal | vauthors = Bande F, Arshad SS, Bejo MH, Moeini H, Omar AR | title = Progress and challenges toward the development of vaccines against avian infectious bronchitis | journal = Journal of Immunology Research | volume = 2015 | article-number = 424860 | year = 2015 | pmid = 25954763 | pmc = 4411447 | doi = 10.1155/2015/424860 | doi-access = free }}</ref> The virus is transmitted by aerosol and food contaminated by feces. Different [[vaccine]]s against IBV exist and have helped to limit the spread of the virus and its variants.<ref name=":14" /> Infectious bronchitis virus is one of a number of strains of the species ''[[Avian coronavirus]]''.<ref>{{Cite web|title=Taxonomy browser (Avian coronavirus)|url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=694014&lvl=3&p=has_linkout&p=blast_url&p=genome_blast&lin=f&keep=1&srchmode=1&unlock|access-date=3 June 2020|website=www.ncbi.nlm.nih.gov}}</ref> Another strain of avian coronavirus is [[turkey coronavirus]] (TCV) which causes [[enteritis]] in [[turkeys]].<ref name=":14" />

Coronaviruses also affect other branches of [[animal husbandry]] such as [[pig farming]] and cattle raising.<ref name=":14" /> [[Swine acute diarrhea syndrome coronavirus]] (SADS-CoV), which is related to [[Rhinolophus bat coronavirus HKU2|bat coronavirus HKU2]], causes [[diarrhea]] in pigs.<ref name="pmid29618817">{{cite journal | vauthors = Zhou P, Fan H, Lan T, Yang XL, Shi WF, Zhang W, Zhu Y, Zhang YW, Xie QM, Mani S, Zheng XS, Li B, Li JM, Guo H, Pei GQ, An XP, Chen JW, Zhou L, Mai KJ, Wu ZX, Li D, Anderson DE, Zhang LB, Li SY, Mi ZQ, He TT, Cong F, Guo PJ, Huang R, Luo Y, Liu XL, Chen J, Huang Y, Sun Q, Zhang XL, Wang YY, Xing SZ, Chen YS, Sun Y, Li J, Daszak P, Wang LF, Shi ZL, Tong YG, Ma JY | title = Fatal swine acute diarrhoea syndrome caused by an HKU2-related coronavirus of bat origin | journal = Nature | volume = 556 | issue = 7700 | pages = 255–58 | date = April 2018 | pmid = 29618817 | doi = 10.1038/s41586-018-0010-9 | pmc = 7094983 | bibcode = 2018Natur.556..255Z | doi-access = free }}</ref> [[Porcine epidemic diarrhea virus]] (PEDV) is a coronavirus that has recently emerged and similarly causes diarrhea in pigs.<ref name="pmid32041637">{{Cite journal | vauthors = Wei X, She G, Wu T, Xue C, Cao Y | title = PEDV enters cells through clathrin-, caveolae-, and lipid raft-mediated endocytosis and traffics via the endo-/lysosome pathway | journal = Veterinary Research | volume = 51 | issue = 1 | article-number = 10 | date = February 2020 | pmid = 32041637 | pmc = 7011528 | doi = 10.1186/s13567-020-0739-7 | doi-access = free }}</ref> [[Transmissible gastroenteritis virus]] (TGEV), which is a member of the species ''Alphacoronavirus 1'',<ref name=":17">{{Cite web|title=Taxonomy browser (Alphacoronavirus 1)|url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Undef&id=693997&lvl=3&lin=f&keep=1&srchmode=1&unlock|access-date=8 June 2020|website=www.ncbi.nlm.nih.gov}}</ref> is another coronavirus that causes diarrhea in young pigs.<ref name="ReferenceA">{{cite journal | vauthors = Cruz JL, Sola I, Becares M, Alberca B, Plana J, Enjuanes L, Zuñiga S | title = Coronavirus gene 7 counteracts host defenses and modulates virus virulence | journal = PLOS Pathogens | volume = 7 | issue = 6 | article-number = e1002090 | date = June 2011 | pmid = 21695242 | pmc = 3111541 | doi = 10.1371/journal.ppat.1002090 | doi-access = free }}</ref><ref name="ReferenceB">{{cite journal | vauthors = Cruz JL, Becares M, Sola I, Oliveros JC, Enjuanes L, Zúñiga S | title = Alphacoronavirus protein 7 modulates host innate immune response | journal = Journal of Virology | volume = 87 | issue = 17 | pages = 9754–67 | date = September 2013 | pmid = 23824792 | pmc = 3754097 | doi = 10.1128/JVI.01032-13 }}</ref> In the cattle industry [[bovine coronavirus]] (BCV), which is a member of the species ''[[Betacoronavirus 1]]'' and related to HCoV-OC43,<ref name=":18">{{Cite web|title=Taxonomy browser (Betacoronavirus 1)|url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=694003&lvl=3&keep=1&srchmode=1&unlock|access-date=8 June 2020|website=www.ncbi.nlm.nih.gov}}</ref> is responsible for severe profuse enteritis in young calves.<ref name=":14" />

=== Domestic pets ===
Coronaviruses infect domestic pets such as cats, dogs, and ferrets.<ref name=":16" /> There are two forms of [[feline coronavirus]] which are both members of the species ''Alphacoronavirus 1''.<ref name=":17" /> Feline enteric coronavirus is a pathogen of minor clinical significance, but spontaneous [[mutation]] of this virus can result in [[feline infectious peritonitis]] (FIP), a disease with high mortality.<ref name=":14" /> There are two different coronaviruses that infect dogs. [[Canine coronavirus]] (CCoV), which is a member of the species ''Alphacoronavirus 1'',<ref name=":17" /> causes mild gastrointestinal disease.<ref name=":14" /> [[Canine coronavirus#Canine respiratory coronavirus|Canine respiratory coronavirus]] (CRCoV), which is a member of the species ''[[Betacoronavirus 1]]'' and related to HCoV-OC43,<ref name=":18" /> cause respiratory disease.<ref name=":14" /> Similarly, there are two types of coronavirus that infect ferrets.<ref>{{Cite web|title=Taxonomy browser (Alphacoronavirus)|url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Undef&id=693996&lvl=3&lin=f&keep=1&srchmode=1&unlock|access-date=8 June 2020|website=www.ncbi.nlm.nih.gov}}</ref> [[Ferret coronavirus|Ferret enteric coronavirus]] causes a gastrointestinal syndrome known as epizootic catarrhal enteritis (ECE), and a more lethal systemic version of the virus (like FIP in cats) known as ferret systemic coronavirus (FSC).<ref>{{Cite web |url=http://www.smallanimalchannel.com/ferrets/ferret-health/whats-new-with-ferret-fiplike-disease.aspx |title=What's New With Ferret FIP-like Disease? |last=Murray |first=Jerry |date=16 April 2014 |format=xls |access-date=24 April 2014 |archive-url=https://web.archive.org/web/20140424203951/http://www.smallanimalchannel.com/ferrets/ferret-health/whats-new-with-ferret-fiplike-disease.aspx |archive-date=24 April 2014 |url-status=live}}</ref><ref>{{Cite web|title=Infectious Diseases of Ferrets - Exotic and Laboratory Animals|url=https://www.merckvetmanual.com/exotic-and-laboratory-animals/ferrets/infectious-diseases-of-ferrets|access-date=8 June 2020|website=Merck Veterinary Manual|language=en-US}}</ref>

=== Laboratory animals ===
Coronaviruses infect laboratory animals.<ref name=":14" /> Mouse hepatitis virus (MHV), which is a member of the species ''[[Murine coronavirus]]'',<ref name=":19">{{Cite web|title=Taxonomy browser (Embecovirus)|url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Undef&id=2509481&lvl=3&lin=f&keep=1&srchmode=1&unlock|access-date=8 June 2020|website=www.ncbi.nlm.nih.gov}}</ref> causes an epidemic [[Murinae|murine]] illness with high mortality, especially among colonies of laboratory mice.<ref name="pmid16339739">{{cite journal|vauthors=Weiss SR, Navas-Martin S|date=December 2005|title=Coronavirus pathogenesis and the emerging pathogen severe acute respiratory syndrome coronavirus|journal=Microbiology and Molecular Biology Reviews|volume=69|issue=4|pages=635–64|doi=10.1128/MMBR.69.4.635-664.2005|pmc=1306801|pmid=16339739 |bibcode=2005MMBR...69..635W }}</ref>  Prior to the discovery of SARS-CoV, MHV was the best-studied coronavirus both ''[[in vivo]]'' and ''[[in vitro]]'' as well as at the molecular level.  Some strains of MHV cause a progressive [[Demyelinating disease|demyelinating encephalitis]] in mice which has been used as a murine model for [[multiple sclerosis]].<ref name="pmid20627412" /> [[Rat coronavirus|Sialodacryoadenitis virus]] (SDAV), which is a strain of the species ''Murine coronavirus'',<ref name=":19" /> is highly infectious coronavirus of laboratory rats, which can be transmitted between individuals by direct contact and indirectly by aerosol.  Rabbit enteric coronavirus causes acute gastrointestinal disease and diarrhea in young [[European rabbits]].<ref name=":14" />  Mortality rates are high.<ref>{{Cite web |url=http://dora.missouri.edu/rabbits/enteric-coronavirus/ |title=Enteric Coronavirus |website=Diseases of Research Animals |access-date=24 January 2020 |archive-url=https://web.archive.org/web/20190701054046/http://dora.missouri.edu/rabbits/enteric-coronavirus/ |archive-date=1 July 2019 |url-status=live}}</ref>

== Prevention and treatment ==
A [[COVID-19 vaccine|number of vaccines]] using different methods have been developed against human coronavirus SARS-CoV-2.<ref name="milken">{{cite web|date=3 November 2020|title=COVID-19 vaccine and treatments tracker (Choose vaccines or treatments tab, apply filters to view select data)|url=https://airtable.com/shrSAi6t5WFwqo3GM/tblEzPQS5fnc0FHYR/viwDBH7b6FjmIBX5x?blocks=hide|access-date=3 November 2020|publisher=Milken Institute}}</ref><ref name="biorender">{{cite web|date=30 October 2020|title=COVID-19 vaccine and therapeutics tracker|url=https://biorender.com/covid-vaccine-tracker|access-date=3 November 2020|publisher=BioRender}}</ref> [[Biological target|Antiviral targets]] against human coronaviruses have also been identified such as viral proteases, polymerases, and entry proteins. [[COVID-19 drug development|Drugs are in development]] which target these proteins and the different steps of viral replication.<ref name="pmid32147628">{{cite journal|vauthors=Dong L, Hu S, Gao J|date=2020|title=Discovering drugs to treat coronavirus disease 2019 (COVID-19)|journal=Drug Discoveries & Therapeutics|volume=14|issue=1|pages=58–60|doi=10.5582/ddt.2020.01012|pmid=32147628|doi-access=free}}</ref><ref name="biorender" />

Vaccines are available for animal coronaviruses IBV, TGEV, and Canine CoV, although their effectiveness is limited. In the case of outbreaks of highly contagious animal coronaviruses, such as PEDV, measures such as [[Culling|destruction of entire herds]] of pigs may be used to prevent transmission to other herds.<ref name="Fehr_2015" />

In December 2025, the World Health Organization released the first unified strategic plan for managing coronavirus disease threats of all types, building upon its work during the COVID-19 pandemic as well as SARS, MERS, and other respiratory viruses.<ref>{{cite news |title=WHO launches new, unified plan for countries to manage coronaviruses: COVID-19 and beyond |url=https://www.who.int/news/item/03-12-2025-WHO-launches-new-unified-plan-for-countries-to-manage-coronaviruses-COVID-19-and-beyond |access-date=4 December 2025 |publisher=World Health Organization |date=3 December 2025 |archive-url=https://web.archive.org/web/20251204154821/https://www.who.int/news/item/03-12-2025-WHO-launches-new-unified-plan-for-countries-to-manage-coronaviruses-COVID-19-and-beyond |archive-date=4 December 2025 |language=en}}</ref>

== See also ==
{{Portal|COVID-19|Viruses}}
* [[Coronavirus diseases]]
* [[Zoonosis]]

== References ==
{{Reflist}}

== Further reading ==
{{Commons category|Orthocoronavirinae}}
{{Wikispecies|Orthocoronavirinae}}
{{Wiktionary}}

{{Refbegin}}
* {{cite book | last=Acheson | first=N. H. | date=2011 | chapter=Chapter 14: Coronaviruses | title=Fundamentals of molecular virology | location=Hoboken, NJ | publisher=John Wiley & Sons | pages=159–171 | isbn=978-0-470-90059-8 }}
* {{cite journal | vauthors = Alwan A, Mahjour J, Memish ZA | title = Novel coronavirus infection: time to stay ahead of the curve | journal = Eastern Mediterranean Health Journal | volume = 19 | pages = S3–4 | date = 2013 | issue = Suppl 1 | pmid = 23888787 | doi = 10.26719/2013.19.supp1.S3 | doi-access = free }}
* {{cite journal | vauthors = Laude H, Rasschaert D, Delmas B, Godet M, Gelfi J, Charley B | title = Molecular biology of transmissible gastroenteritis virus | journal = Veterinary Microbiology | volume = 23 | issue = 1–4 | pages = 147–54 | date = June 1990 | pmid = 2169670 | doi = 10.1016/0378-1135(90)90144-K | pmc = 7117338 }}
* {{cite journal | vauthors = Sola I, Alonso S, Zúñiga S, Balasch M, Plana-Durán J, Enjuanes L | title = Engineering the transmissible gastroenteritis virus genome as an expression vector inducing lactogenic immunity | journal = Journal of Virology | volume = 77 | issue = 7 | pages = 4357–69 | date = April 2003 | pmid = 12634392 | pmc = 150661 | doi = 10.1128/JVI.77.7.4357-4369.2003 }}
* {{cite journal |last1=Tajima |first1=M. |title=Morphology of transmissible gastroenteritis virus of pigs |journal=Archiv für die gesamte Virusforschung |date=1970 |volume=29 |pages=105–108 |doi=10.1007/BF01253886 |pmid=4195092 |pmc=7086923 }}
{{Refend}}

{{Medical resources
|ICD10 = {{ICD10|B97.2}}
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{{Common cold}}
{{Viral diseases}}
{{Coronaviridae}}
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[[Category:Coronaviruses| ]]
[[Category:Animal virology]]
[[Category:Coronaviridae| ]]
[[Category:Virus subfamilies]]