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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. Unlike other coronaviruses, viruses in this subgenus also have an additional shorter spike-like structural protein called hemagglutinin esterase (HE).
Recombination
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. Contributing to this diversity are several recombination events that had taken place in the past between closely related Beta-CoVs of the subgenus Embecovirus.
^ "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.
^ Woo, Patrick C. Y.; Huang, Yi; Lau, Susanna K. P.; Yuen, Kwok-Yung (2010-08-24). "Coronavirus Genomics and Bioinformatics Analysis". Viruses. 2 (8): 1804–1820. doi:10.3390/v2081803. ISSN1999-4915. PMC3185738. PMID21994708. 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).
Wong, Antonio C. P.; Li, Xin; Lau, Susanna K. P.; Woo, Patrick C. Y. (2019-02-20). "Global Epidemiology of Bat Coronaviruses". Viruses. 11 (2): 174. doi:10.3390/v11020174. ISSN1999-4915. PMC6409556. PMID30791586. 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 . 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) . In addition, a fifth subgenus, Hibecovirus, was also included (Figure 1) .
Lai, Michael M. C.; Cavanagh, David (1997-01-01), Maramorosch, Karl; Murphy, Frederick A.; Shatkin, Aaron J. (eds.), "The Molecular Biology of Coronaviruses; III. Structure of Virions; A. Virion Morphology", Advances in Virus Research, 48, Academic Press: 5–6, doi:10.1016/S0065-3527(08)60286-9, PMC7130985, PMID9233431
Woo, Patrick C. Y.; Huang, Yi; Lau, Susanna K. P.; Yuen, Kwok-Yung (2010-08-24). "Coronavirus Genomics and Bioinformatics Analysis". Viruses. 2 (8): 1804–1820. doi:10.3390/v2081803. ISSN1999-4915. PMC3185738. PMID21994708. 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.
^ Diversity 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
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