Raccoon dog was proposed as a potential host of SARS-CoV-2, but no evidence support such a notion. In our study, we investigated the binding affinities of raccoon dog ACE2 (rdACE2) to the spike (S) protein receptor binding domain (RBD) of SARS-CoV-2 prototype (PT) and its variants. It revealed that the binding affinities of RBD from SARS-CoV-2 variants were generally lower than that of the PT RBD. Through structural and functional analyses, we found amino acids H34 and M82 play pivotal roles in maintaining the binding affinity of ACE2 to different SARS-CoV-2 sub-variants. These results suggest that raccoon dogs exhibit lower susceptibility to SARS-CoV-2 compared to those animal species with a high prevalence of SARS-CoV-2 transmission.

Author Summary

In our study, we investigated the potential role of raccoon dogs as hosts for SARS-CoV-2 by examining the binding affinities between the spike (S) protein receptor binding domain (RBD) of SARS-CoV-2 prototype (PT) and its variants with the ACE2 receptor from raccoon dogs (rdACE2). Our findings revealed that the binding affinities of the RBD from most of SARS-CoV-2 variants to rdACE2 were generally lower compared to the PT RBD. Detailed structural and functional analyses identified two key amino acids, H34 and M82, which are crucial in preserving the binding affinity of ACE2 to different SARS-CoV2 sub-variants. These results indicate that raccoon dogs have a lower susceptibility to SARS-CoV-2 compared to other animal species known for a high prevalence of SARSCoV-2 transmission. This study provides valuable insights into the host range of SARSCoV-2 and highlights the importance of specific amino acid residues in ACE2 for virusreceptor interactions. Understanding these interactions is essential for assessing the zoonotic potential of SARS-CoV-2 and implementing effective measures to prevent interspecies transmission of the virus.