Cryo-EM structure of coronavirus-HKU1 haemagglutinin esterase reveals architectural changes arising from prolonged circulation in humans

Human coronavirus-HKU1 contains two surface projections called spike and haemagglutinin-esterase (HE), with the latter acting as a receptor-destroying enzyme. Here, the authors use cryo-EM and mass spectrometry to characterise the small, heavily glycosylated HKU1 HE, revealing a vestigial lectin domain covered with a putative glycan shield; and they discuss these features in the context of host adaptation.