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.[7] Unlike other coronaviruses, viruses in this subgenus also have an additional shorter spike-like structural protein called hemagglutinin esterase (HE).[2][8]
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.[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]
↑"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.
12Woo, 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 [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].
↑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.
12Diversity 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
