Following the outbreak of coronavirus disease 2019 (COVID-19), several severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related coronaviruses have been discovered. Previous research has identified a novel lineage of SARS-CoV-2-related CoVs in bats, including RsYN04, which recognizes human angiotensin-converting enzyme 2 (ACE2) and thus poses a potential threat to humans. Here, we screened the binding of the RsYN04 receptor-binding domain (RBD) to ACE2 orthologs from 52 animal species and found that the virus showed a narrower ACE2-binding spectrum than SARS-CoV-2. However, the presence of the T484W mutation in the RsYN04 RBD broadened its range. We also evaluated 44 SARS-CoV-2 antibodies targeting seven epitope communities in the SARS-CoV-2 RBD, together with serum obtained from COVID-19 convalescents and vaccinees, to determine their cross-reaction against RsYN04. Results showed that no antibodies, except for the RBD-6 and RBD-7 classes, bound to the RsYN04 RBD, indicating substantial immune differences from SARS-CoV-2. Furthermore, the structure of the RsYN04 RBD in complex with cross-reactive antibody S43 in RBD-7 revealed a potently broad epitope for the development of therapeutics and vaccines. Our findings suggest RsYN04 and other viruses belonging to the same clade have the potential to infect several species, including humans, highlighting the necessity for viral surveillance and development of broad anti-coronavirus countermeasures.
自新型冠状病毒病疫情（coronavirus disease 2019, COVID-19）暴发以来，相继发现多种动物源冠状病毒。目前众多证据表明新型冠状病毒（severe acute respiratory syndrome coronavirus 2，SARS-CoV-2）可能起源于蝙蝠冠状病毒，因此能结合人血管紧张素转换酶2（angiotensin-converting enzyme 2，ACE2）受体的蝙蝠冠状病毒具有感染人的潜在风险。前期研究发现，蝙蝠冠状病毒RsYN04可以结合人ACE2，因而表明其具有外溢导致人感染的风险。针对SARS-CoV-2，目前已开发多种治疗性抗体及疫苗，而这些治疗手段或预防措施能否用于抵抗RsYN04引起的疾病，则需要进行进一步的研究。基于以上背景，该文开展了对RsYN04的跨种识别及与SARS-CoV-2的交叉免疫原性的研究。该研究选择了52个与人类生活密切相关的物种，包括宠物、家畜、野生动物等，通过探究它们与人ACE2受体同源蛋白同RsYN04的受体结合域（receptor-binding domain, RBD）的结合情况，发现RsYN04的ACE2结合谱窄于SARS-CoV-2的ACE2结合谱，但是T484W单点突变的引入可以显著扩大RsYN04的受体结合谱。此外，该研究系统地筛查了识别SARS-CoV-2 RBD七类表位的44株单克隆中和抗体，以及新冠康复患者和疫苗接种者血清，以确定它们对于RsYN04的交叉反应性，发现大多数单克隆抗体并不能结合RsYN04 RBD或结合能力相较于SARS-CoV-2大幅下降，表明RsYN04与SARS-CoV-2的免疫原性具有显著差异；同时，解析了一株团队前期研究发现的广谱结合抗体S43与RsYN04 RBD的复合物结构，揭示了其广谱结合机制。以上研究发现提示了RsYN04具有跨种传播风险，因而需要加强对RsYN04的监测，以防止病毒外溢引发新的传染病疫情，同时提示需要研发针对RsYN04或沙贝病毒的广谱药物和疫苗。.
Keywords: ACE2; Antibody; RsYN04; SARS-CoV-2-related coronavirus; Structure.