The Rhinolophus affinis bat ACE2 and multiple animal orthologs are functional receptors for bat coronavirus RaTG13 and SARS-CoV-2

蝙蝠中菊头ACE2蛋白和多个动物ACE2是蝙蝠病毒RaTG13和新冠病毒的功能受体

Bat coronavirus(CoV)RaTG13 shares the highest genome sequence identity with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)among all known coronaviruses,and also uses human angiotensin converting enzyme 2(hACE2)for virus entry.Thus,SARS-CoV-2 is thought to have originated from bat.However,whether SARS-CoV-2 emerged from bats directly or through an intermediate host remains elusive.Here,we found that Rhinolophus affinis bat ACE2(Ra ACE2)is an entry receptor for both SARSCoV-2 and Ra TG13,although the binding of Ra ACE2 to the receptor-binding domain(RBD)of SARSCoV-2 is markedly weaker than that of h ACE2.We further evaluated the receptor activities of ACE2 s from additional 16 diverse animal species for Ra TG13,SARS-CoV,and SARS-CoV-2 in terms of S protein binding,membrane fusion,and pseudovirus entry.We found that the Ra TG13 spike(S)protein is significantly less fusogenic than SARS-CoV and SARS-CoV-2,and seven out of sixteen different ACE2 s function as entry receptors for all three viruses,indicating that all three viruses might have broad host rages.Of note,Ra TG13 S pseudovirions can use mouse,but not pangolin ACE2,for virus entry,whereas SARS-CoV-2 S pseudovirions can use pangolin,but not mouse,ACE2 enter cells efficiently.Mutagenesis analysis revealed that residues 484 and 498 in Ra TG13 and SARS-CoV-2 S proteins play critical roles in recognition of mouse and human ACE2 s.Finally,two polymorphous Rhinolophous sinicus bat ACE2 s showed different susceptibilities to virus entry by Ra TG13 and SARS-CoV-2 S pseudovirions,suggesting possible coevolution.Our results offer better understanding of the mechanism of coronavirus entry,host range,and virushost coevolution.

新冠病毒可能起源于蝙蝠,但是否存在中间宿主以及可能的中间宿主是什么,目前还没有明确答案.来自于中菊头蝙蝠的冠状病毒RaT G13是所有已知冠状病毒中与新冠病毒基因组同源性最高的,被认为可能是新冠病毒的起源.本研究首次报道中菊头angiotensin-converting enzyme 2(ACE2)不仅能介导RaT G13入侵,也能介导新冠病毒入侵,但新冠病毒受体结合区(Receptor binding domain,RBD)与中菊头ACE2的亲和力明显比人ACE2低.随后,本研究评估了来自9个目16个不同物种的ACE2作为RaT G13、新冠病毒以及SARS病毒的入侵受体的可能性,发现7个物种的ACE2能介导所有三种病毒的入侵,提示这三个病毒可能具有较广的宿主范围.另外,本研究发现RaT G13和新冠病毒S蛋白在结合小鼠和穿山甲ACE2时存在明显差异.进一步研究发现病毒S蛋白的第484和498位氨基酸对识别小鼠ACE2至关重要.该研究对深入了解冠状病毒入侵、宿主范围以及病毒宿主共进化的机制具有积极意义.