Broad Host Range of SARS-CoV-2 Predicted by Comparative and Structural Analysis of ACE2 in Vertebrates

Joana Damas; Graham M. Hughes; Kathleen C. Keough; Corrie A. Painter; Nicole S. Persky; Marco Corbo; Michael Hiller; Klaus-Peter Koepfli; Andreas R. Pfenning; Huabin Zhao; Diane P. Genereux; Ross Swofford; Katherine S. Pollard; Oliver A. Ryder; Martin T. Nweeia; Kerstin Lindblad-Toh; Emma C. Teeling; Elinor K. Karlsson; Harris A. Lewin

Several recent studies examined the role of ACE2 in SARS-CoV-2 binding and cellular infection, and its relationship to experimental and natural infections in different species (30, (41) (42) (43) (44) (45) (46) . Our study design differs substantially from those studies in several aspects: 1) we analyzed a larger number of primates, carnivores, rodents, cetartiodactyls and other mammalian orders, and an extensive phylogenetic sampling of fishes, birds, amphibians and reptiles; 2) we analyzed the full complement of S-binding residues across the ACE2 binding site, which was based on a consensus set from two independent studies (13, 21) ; 3) we used different methodologies to assess ACE2 binding capacity for SARS-CoV-2 S; and, 4) our study tested for selection and accelerated evolution across the entire ACE2 protein. While our results are strongly consistent with the results and conclusions of Melin and colleagues (44) on the predicted susceptibility of primates to SARS-CoV-2, particularly Old World primates, our work made predictions for a larger number of primates (N=39 vs N=27), bats (N=37 vs N=7), other mammals (N=176 vs N=5) and other vertebrates (N=158 vs N=0). When ACE2 from species in our study were compared with results of other studies there were many consistencies, such as for rodents, but some predictions that differ, such as the relatively high risk described for SARS-CoV-2 binding in pangolin and horse (45) , civet (46) , Rhinolophus sinicus bats (46) and turtles (45) . In one recent study, binding affinity of soluble ACE2 for the SARS-CoV-2 S RBD was analyzed by saturation mutagenesis (26) . Results obtained at each ACE2 binding residue were generally consistent with ours, particularly in the binding hotspot region of ACE2 residues 353-357. Importantly, as compared with other studies, our results greatly expanded the potential number of intermediate hosts and identified many more threatened species that could be infected by SARS-CoV-2 via their ACE2 receptors.