Hence, sugar-binding S1-NTDs across different coronavirus genera may share the same galectine fold but have diverged to recognize different sugar receptors. On the other hand,  β-genus  MHV S1-NTD has evolved specificity for a novel protein receptor, CEACAM1. Subsequently, MHV S1-NTD lost its lectin activity because proteins in general have advantages over sugars as viral receptors by providing higher affinity and specificity for viral attachment.