Embecovirus | |
---|---|
Murine coronavirus (MHV) virion electron micrograph, schematic structure, and genome. | |
Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Pisuviricota |
Class: | Pisoniviricetes |
Order: | Nidovirales |
Family: | Coronaviridae |
Genus: | Betacoronavirus |
Subgenus: | Embecovirus |
Species [1] | |
Embecovirus is a subgenus of coronaviruses in the genus Betacoronavirus . [1] The viruses in this subgenus, unlike other coronaviruses, have a hemagglutinin esterase (HE) gene. [2] The viruses in the subgenus were previously known as group 2a coronaviruses. [3] [4]
The viruses of this subgenus, like other coronaviruses, have a lipid bilayer envelope in which the membrane (M), envelope (E) and spike (S) structural proteins are anchored. [5] Unlike other coronaviruses, viruses in this subgenus also have an additional shorter spike-like structural protein called hemagglutinin esterase (HE). [2] [6]
Genetic recombination can occur when two or more viral genomes are present in the same host cell. The dromedary camel beta-coronavirus (Beta-CoV HKU23) exhibits genetic diversity in the African camel population. [7] Contributing to this diversity are several recombination events that had taken place in the past between closely related Beta-CoVs of the subgenus Embecovirus. [7]
Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the common cold, while more lethal varieties can cause SARS, MERS and COVID-19, which is causing the ongoing pandemic. In cows and pigs they cause diarrhea, while in mice they cause hepatitis and encephalomyelitis.
Severe acute respiratory syndrome–related coronavirus is a species of virus consisting of many known strains phylogenetically related to severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) that have been shown to possess the capability to infect humans, bats, and certain other mammals. These enveloped, positive-sense single-stranded RNA viruses enter host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor. The SARSr-CoV species is a member of the genus Betacoronavirus and of the subgenus Sarbecovirus.
Coronaviridae is a family of enveloped, positive-strand RNA viruses which infect amphibians, birds, and mammals. The group includes the subfamilies Letovirinae and Orthocoronavirinae; the members of the latter are known as coronaviruses.
Murine coronavirus (M-CoV) is a virus in the genus Betacoronavirus that infects mice. Belonging to the subgenus Embecovirus, murine coronavirus strains are enterotropic or polytropic. Enterotropic strains include mouse hepatitis virus (MHV) strains D, Y, RI, and DVIM, whereas polytropic strains, such as JHM and A59, primarily cause hepatitis, enteritis, and encephalitis. Murine coronavirus is an important pathogen in the laboratory mouse and the laboratory rat. It is the most studied coronavirus in animals other than humans, and has been used as an animal disease model for many virological and clinical studies.
In virology, a spike protein or peplomer protein is a protein that forms a large structure known as a spike or peplomer projecting from the surface of an enveloped virus. The proteins are usually glycoproteins that form dimers or trimers.
The Coronavirus packaging signal is a conserved cis-regulatory element found in Betacoronavirus. It has an important role in regulating the packaging of the viral genome into the capsid. As part of the viral life cycle, within the infected cell, the viral genome becomes associated with viral proteins and assembles into new infective progeny viruses. This process is called packaging and is vital for viral replication.
Transmissible gastroenteritis virus or Transmissible gastroenteritis coronavirus (TGEV) is a coronavirus which infects pigs. It is an enveloped, positive-sense, single-stranded RNA virus which enters its host cell by binding to the APN receptor. The virus is a member of the genus Alphacoronavirus, subgenus Tegacovirus, species Alphacoronavirus 1.
Bovine coronavirus is a coronavirus which is a member of the species Betacoronavirus 1. The infecting virus is an enveloped, positive-sense, single-stranded RNA virus which enters its host cell by binding to the N-acetyl-9-O-acetylneuraminic acid recepter. Infection causes calf enteritis and contributes to the enzootic pneumonia complex in calves. It can also cause winter dysentery in adult cattle. It can infect both domestic and wild ruminants and has a worldwide distribution. Transmission is horizontal, via oro-fecal or respiratory routes. Like other coronaviruses from genus Betacoronavirus, subgenus Embecovirus, it has a surface protein called hemagglutinin esterase (HE) in addition to the four structural proteins shared by all coronaviruses.
Pipistrellus bat coronavirus HKU5 is an enveloped, positive-sense single-stranded RNA mammalian Group 2 Betacoronavirus discovered in Japanese Pipistrellus in Hong Kong. This strain of coronavirus is closely related to the newly identified novel MERS-CoV that is responsible for the 2012 Middle East respiratory syndrome-related coronavirus outbreaks in Saudi Arabia, Jordan, United Arab Emirates, the United Kingdom, France, and Italy.
Human coronavirus HKU1 (HCoV-HKU1) is a species of coronavirus in humans and animals. It causes an upper respiratory disease with symptoms of the common cold, but can advance to pneumonia and bronchiolitis. It was first discovered in January 2004 from one man in Hong Kong. Subsequent research revealed it has global distribution and earlier genesis.
Betacoronavirus is one of four genera of coronaviruses. Member viruses are enveloped, positive-strand RNA viruses that infect mammals. The natural reservoir for betacoronaviruses are bats and rodents. Rodents are the reservoir for the subgenus Embecovirus, while bats are the reservoir for the other subgenera.
Human coronavirus OC43 (HCoV-OC43) is a member of the species Betacoronavirus 1, which infects humans and cattle. The infecting coronavirus is an enveloped, positive-sense, single-stranded RNA virus that enters its host cell by binding to the N-acetyl-9-O-acetylneuraminic acid receptor. OC43 is one of seven coronaviruses known to infect humans. It is one of the viruses responsible for the common cold and may have been responsible for the 1889–1890 pandemic. It has, like other coronaviruses from genus Betacoronavirus, subgenus Embecovirus, an additional shorter spike protein called hemagglutinin-esterase (HE).
Alphacoronaviruses (Alpha-CoV) are members of the first of the four genera of coronaviruses. They are positive-sense, single-stranded RNA viruses that infect mammals, including humans. They have spherical virions with club-shaped surface projections formed by trimers of the spike protein, and a viral envelope.
Betacoronavirus 1 is a species of coronavirus which infects humans and cattle. The infecting virus is an enveloped, positive-sense, single-stranded RNA virus and is a member of the genus Betacoronavirus and subgenus Embecovirus. Like other embecoviruses, it has an additional shorter spike-like surface protein called hemagglutinin esterase (HE) as well as the larger coronavirus spike protein.
Human coronavirus 229E (HCoV-229E) is a species of coronavirus which infects humans and bats. It is an enveloped, positive-sense, single-stranded RNA virus which enters its host cell by binding to the APN receptor. Along with Human coronavirus OC43, it is one of the viruses responsible for the common cold. HCoV-229E is a member of the genus Alphacoronavirus and subgenus Duvinacovirus.
Tylonycteris bat coronavirus HKU4 is an enveloped, positive-sense single-stranded RNA virus mammalian Group 2 Betacoronavirus that has been found to be genetically related to the Middle East respiratory syndrome-related coronavirus (MERS-CoV) that is responsible for the 2012 Middle East respiratory syndrome coronavirus outbreak in Saudi Arabia, Jordan, United Arab Emirates, the United Kingdom, France, and Italy.
Rousettus bat coronavirus HKU9 (HKU9-1) is an enveloped, positive-sense, single-stranded RNA mammalian Group 2 Betacoronavirus discovered in Rousettus bats in China in 2011. This strain of coronavirus is closely related to the EMC/2012 strain found in London which is related to the Middle East respiratory syndrome-related coronavirus (MERS-CoV). The MERS-CoV species is responsible for the 2012 Middle East respiratory syndrome coronavirus outbreak in Saudi Arabia, Jordan, United Arab Emirates, the United Kingdom, France, and Italy.
Rhinolophus bat coronavirus HKU2 is a novel enveloped, single-stranded positive-sense RNA virus species in the Alphacoronavirus, or Group 1, genus with a corona-like morphology.
Merbecovirus is a subgenus of viruses in the genus Betacoronavirus, including the human pathogen Middle East respiratory syndrome–related coronavirus (MERS-CoV). The viruses in this subgenus were previously known as group 2c coronaviruses.
Nobecovirus is a subgenus of viruses in the genus Betacoronavirus. The viruses in the group were previously known as group 2d coronaviruses.
In all members of Betacoronavirus subgroup A, a haemagglutinin esterase (HE) gene, which encodes a glycoprotein with neuraminate O-acetyl-esterase activity and the active site FGDS, is present downstream to ORF1ab and upstream to S gene (Figure 1).
See figure 2.
CoVs are classified into four genera, Alphacoronavirus, Betacoronavirus, Gammacoronavirus and Deltacoronavirus. Within Betacoronavirus, they can be further subclassified into lineages A, B, C and D [1]. In 2018, these four lineages were reclassified as subgenera of Betacoronavirus, and renamed as Embecovirus (previous lineage A), Sarbecovirus (previous lineage B), Merbecovirus (previous lineage C) and Nobecovirus (previous lineage D) [2]. In addition, a fifth subgenus, Hibecovirus, was also included (Figure 1) [2].
The presence of HE genes exclusively in members of Betacoronavirus subgroup A, but not members of Betacoronavirus subgroup B, C and D suggested that the recombination had probably occurred in the ancestor of members of Betacoronavirus subgroup A, after diverging from the ancestor of other subgroups of Betacoronavirus.