Abstract：Severe acute respiratory syndrome coronavirus (SARSCoV) is a highly pathogenic virus which originated from bat SARSlike coronavirus (SLCoV) and infects humans. Angiotensinconverting enzyme 2 (ACE2), the functional receptor of SARSCoV, is a key molecular affecting SARSCoV pathogenesis, host range, and crossspecies transmission. Previous studies demonstrated that SARSCoV and some SLCoV strains (such as WIV1) can use human, civet, and bat ACE2 to enter cells, while SARSCoV utilizes mouse ACE2 less effectively. Though rodents are the most diverse mammals and the most popular experimental model, the utilization of mouse ACE2 by SLCoV has not been revealed. In the present study, pseudoviral infection experiments were conducted to compare SARSCoV BJ01 and SLCoV WIV1 on their ability of using human, civet, bat, mouse ACE2 and ACE2 mutants to enter cells. Meanwhile, the binding between receptorbinding domain (RBD) of the two viruses and different ACE2 was verified by protein binding experiments. The results showed that SLCoV WIV1 can use mouse ACE2 to enter cells, and WIV1 RBD binds to mouse ACE2 as efficiently as human and civet ACE2 whereas more strongly than bat ACE2. The L440P mutation of ACE2 in different species can significantly reduce the ability of RBD binding and the efficiency of pseudovirus invasion. The studies indicate that mouse ACE2 is a functional receptor for SLCoV WIV1 and L440 of ACE2 is a key amino acid site affecting interspecies infection. The study is helpful to further understand the receptor recognition and crossspecies transmission mechanism of SLCoV, and will be beneficial to the prevention and control of similar CoV in the future.
