Fig. 4. Characterization of the binding affinity between mouse ACE2 and Omicron spike trimmers.
a–c Binding of Omicron BA.2 (a), Omicron BA.1(b) and WT (c) spike trimers to mouse ACE2 as determined by BLI. d The KD values of tested pairs in this study as determined by BLI. e Amino acid alignment of the 16 key residues in hACE2 with 4 ACE2 orthologs from mouse, cat, rat, and dog. f Superposition of the structures of human ACE2 bound Omicron BA.2 spike trimer and the cat ACE2 bound original spike trimer. g, h The binding modes of dog (g) and rat (h) ACE2s with the BA.2 RBD, were generated based on the complex structure of human ACE2 bound Omicron BA.2 spike trimer. The different residues among ACE2 protein that are responsible for the interactions with SARS-CoV-2 spike protein are shown with detained interactions.