| Embecovirus | |
|---|---|
 | |
| Murine coronavirus (MHV)virionelectron 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 |
Embecovirus is asubgenus ofcoronaviruses in the genusBetacoronavirus.[1] The viruses in this subgenus, unlike othercoronaviruses, have ahemagglutinin esterase (HE) gene.[2] The viruses in the subgenus were previously known asgroup 2a coronaviruses.[3][4]
The subgenus contains the following species, listed by scientific name and followed by the exemplar virus of the species:[5][6]
The viruses of this subgenus, like other coronaviruses, have a lipid bilayerenvelope in which themembrane (M),envelope (E) andspike (S) structural proteins are anchored.[7] Unlike other coronaviruses, viruses in this subgenus also have an additional shorter spike-like structural protein calledhemagglutinin esterase (HE).[2][8]
Genetic recombination can occur when two or more viralgenomes are present in the same host cell. Thedromedary camel beta-coronavirus (Beta-CoV HKU23) exhibits genetic diversity in theAfrican camel population.[9] Contributing to this diversity are several recombination events that had taken place in the past between closely related Beta-CoVs of the subgenus Embecovirus.[9]
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.
Taxonomy of theCoronaviridae | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Higher taxonomy:Riboviria >Orthornavirae >Pisuviricota >Pisoniviricetes >Nidovirales >Cornidovirineae >Coronaviridae | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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