Sugimoto Satoko, Kakizaki Masatoshi, Kawase Miyuki, Kawachi Kengo, Ujike Makoto, Kamitani Wataru, Sentsui Hiroshi, Shirato Kazuya
Department of Virology III, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan.
Management Department of Biosafety, Laboratory Animals, and Pathogen Bank, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan.
Microbiol Spectr. 2023 Feb 6;11(2):e0459022. doi: 10.1128/spectrum.04590-22.
Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus that causes MERS, which is endemic in the Middle East. The absence of human cases in Africa despite the presence of MERS-CoV suggests virological differences between MERS-CoVs in Africa and the Middle East. In fact, in the laboratory, recombinant MERS-CoV carrying the spike (S) protein of Ethiopian isolates exhibits attenuated properties, being more easily neutralized and replicating slower than viruses carrying the S protein of Middle Eastern isolate, EMC. In this study, to identify the amino acids that define the different virological features between Ethiopian and Middle Eastern MERS-CoVs, neutralization titers and viral replication were evaluated using recombinant MERS-CoVs carrying amino acid substitution(s) in the S protein. A single amino acid difference introduced into the receptor binding domain was sufficient to reverse the difference in the neutralizing properties of the S protein between Ethiopian and Middle Eastern MERS-CoVs. Furthermore, amino acid mutations in the S1 and S2 regions of S protein were collectively involved in slow viral replication. Since even a single amino acid difference in S protein can reverse the viral properties of MERS-CoV, it should be noted that multiple mutations may induce a significant change. Careful monitoring of genetic alterations in MERS-CoVs in Africa is therefore required to detect the emergence of virulent strains generated by a few genetic differences. There have been no reported cases of human Middle East respiratory syndrome (MERS) in Africa, despite the presence of MERS coronavirus (MERS-CoV). Previous studies have shown that recombinant MERS-CoV carrying the S protein of an Ethiopian isolate replicated slower and was more easily neutralized relative to MERS-CoV carrying the S protein of a Middle Eastern isolate. In this study, we investigated the amino acid(s) in S protein associated with the different viral characteristics between Ethiopian and Middle Eastern MERS-CoVs. The results revealed that a single amino acid difference in the receptor binding domain was sufficient to reverse the neutralization profile. This implies that slight genetic changes can alter the predominant population of MERS-CoV, similar to the transition of variants of severe acute respiratory syndrome coronavirus-2. Careful genetic monitoring of isolates is important to detect the spread of possible virulent MERS-CoVs generated by mutation(s).
中东呼吸综合征冠状病毒（MERS-CoV）是一种人畜共患病毒，可引发中东地区地方性流行的中东呼吸综合征（MERS）。尽管非洲存在MERS-CoV，但却没有人类病例，这表明非洲和中东的MERS-CoV在病毒学上存在差异。事实上，在实验室中，携带埃塞俄比亚分离株刺突（S）蛋白的重组MERS-CoV表现出减毒特性，比携带中东分离株EMC的S蛋白的病毒更易被中和且复制速度更慢。在本研究中，为了确定定义埃塞俄比亚和中东MERS-CoV之间不同病毒学特征的氨基酸，使用在S蛋白中携带氨基酸替换的重组MERS-CoV评估了中和效价和病毒复制情况。引入受体结合域的单个氨基酸差异足以逆转埃塞俄比亚和中东MERS-CoV的S蛋白在中和特性上的差异。此外，S蛋白S1和S2区域的氨基酸突变共同导致病毒复制缓慢。由于S蛋白中即使单个氨基酸差异也能逆转MERS-CoV的病毒特性，因此应注意多个突变可能会引起显著变化。因此，需要仔细监测非洲MERS-CoV的基因改变，以检测由少数基因差异产生的毒力菌株的出现。尽管存在中东呼吸综合征冠状病毒（MERS-CoV），但非洲尚无人类中东呼吸综合征（MERS）病例报告。先前的研究表明，与携带中东分离株S蛋白的MERS-CoV相比，携带埃塞俄比亚分离株S蛋白的重组MERS-CoV复制较慢且更易被中和。在本研究中，我们调查了S蛋白中与埃塞俄比亚和中东MERS-CoV之间不同病毒特征相关的氨基酸。结果显示，受体结合域的单个氨基酸差异足以逆转中和情况。这意味着轻微的基因变化可以改变MERS-CoV的主要群体，类似于严重急性呼吸综合征冠状病毒2变体的转变。仔细监测分离株的基因对于检测可能由突变产生的毒力MERS-CoV的传播很重要。
