Betacoronavirus Adaptation to Humans Involved Progressive Loss of Hemagglutinin-Esterase Lectin Activity

Publication date: 8 March 2017
Source:Cell Host & Microbe, Volume 21, Issue 3
Author(s): Mark J.G. Bakkers, Yifei Lang, Louris J. Feitsma, Ruben J.G. Hulswit, Stefanie A.H. de Poot, Arno L.W. van Vliet, Irina Margine, Jolanda D.F. de Groot-Mijnes, Frank J.M. van Kuppeveld, Martijn A. Langereis, Eric G. Huizinga, Raoul J. de Groot
Human beta1-coronavirus (β1CoV) OC43 emerged relatively recently through a single zoonotic introduction. Like related animal β1CoVs, OC43 uses 9-O-acetylated sialic acid as receptor determinant. β1CoV receptor binding is typically controlled by attachment/fusion spike protein S and receptor-binding/receptor-destroying hemagglutinin-esterase protein HE. We show that following OC43's introduction into humans, HE-mediated receptor binding was selected against and ultimately lost through progressive accumulation of mutations in the HE lectin domain. Consequently, virion-associated receptor-destroying activity toward multivalent glycoconjugates was reduced and altered such that some clustered receptor populations are no longer cleaved. Loss of HE lectin function was also observed for another respiratory human coronavirus, HKU1. This thus appears to be an adaptation to the sialoglycome of the human respiratory tract and for replication in human airways. The findings suggest that the dynamics of virion-glycan interactions contribute to host tropism. Our observations are relevant also to other human respiratory viruses of zoonotic origin, particularly influenza A virus.

Graphical abstract

Teaser

Coronavirus OC43 entered the human population relatively recently. Bakkers et al. report that as an adaptation to replication in human airways, the OC43 hemagglutinin-esterase lost its receptor-binding function. Consequently, virion-associated receptor-destroying activity toward clustered sialoglycan-based receptor determinants was reduced. Suggestive of convergent evolution, human respiratory coronavirus HKU1 underwent similar changes.


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