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]
Recombination
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]
^ ab"Virus Taxonomy: 2018 Release". International Committee on Taxonomy of Viruses (ICTV). October 2018. Archived from the original on 4 March 2018. Retrieved 24 January 2019.
. 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).
. 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.
^ abDiversity of Dromedary Camel Coronavirus HKU23 in African Camels Revealed Multiple Recombination Events among Closely Related Betacoronaviruses of the Subgenus Embecovirus. So RTY, et al. J Virol. 2019. PMID 31534035
