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Wang P, Ding P, Wei Q, Liu H, Liu Y, Li Q, Xing Y, Li G, Zhou E, Zhang G. Precise location of two novel linear epitopes on the receptor-binding domain surface of MERS-CoV spike protein recognized by two different monoclonal antibodies. Int J Biol Macromol 2022; 195:609-619. [PMID: 34871658 PMCID: PMC8641979 DOI: 10.1016/j.ijbiomac.2021.11.192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/25/2021] [Accepted: 11/27/2021] [Indexed: 11/15/2022]
Abstract
Middle East respiratory syndrome coronavirus (MERS-CoV) is a coronavirus which can cause severe human respiratory diseases with a fatality rate of almost 36%. In this study, we report the generation, characterization and epitope mapping of several monoclonal antibodies against the spike receptor-binding domain (RBD) of MERS-CoV. Two monoclonal antibodies (4C7 and 6E8) that can react with linearized RBD have been selected for subsequent identification of RBD mAb-binding epitopes. Two distinct novel linear epitopes, 423FTCSQIS429 and 546SPLEGGGWL554,were precisely located at the outermost surface of RBD by dot-blot hybridization and ELISAs. Multiple sequence alignment analysis showed that these two peptides were highly conserved. Alanine (A)-scanning mutagenesis demonstrated that residues 423F, 428I, and 429S are the crucial residues for the linear epitope 423FTCSQIS429 while residues 548L, 550G, 553W, 554L for epitope 546SPLEGGGWL554. These findings may be helpful for further understanding of the function of RBD protein and the development of subsequent diagnosis and detection methods.
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Affiliation(s)
- Pan Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China,Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | - Peiyang Ding
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Qiang Wei
- Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | - Hongliang Liu
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Yunchao Liu
- Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | - Qingmei Li
- Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | - Yunrui Xing
- Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | - Ge Li
- Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | - Enmin Zhou
- College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China
| | - Gaiping Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China; Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China; School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China; College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China.
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Abstract
Mouse DPP4 (mDPP4) receptor is not a functional receptor for MERS-CoV while human DPP4 (hDPP4) is, despite the high similarities between hDPP4 and mDPP4 receptors. The variability of DPP4 receptors against MERS-CoV is not fully investigated, especially conformational and structural differences. Therefore, investigating the conformational differences of the DPP4 receptors can aid in developing new small animal models for MERS-CoV vaccines and antiviral agents evaluation. Here we used MD simulations and docking techniques to investigate these structural differences in DPP4 receptors. The results showed chimeric mouse mDPP4 (cmDPP4) has a similar compact conformation as wild-type hDPP4 based on the structural analysis. Interestingly, a single Thr288Ala mutation induced a relaxed conformation in chimeric 2 hDPP4 (c2hDPP4) and chimeric 2 mDPP4 (c2mDPP4); in addition to its significant effect on the DPP4 flexibility. The Thr288 residue is known for its critical function in MERS-CoV RBD interaction. Moreover, MERS-CoV RBD adopts a "standing" conformation when docked to hDPP4 and cmDPP4 in blade IV and V regions. In conclusion, the results could explain the functionality differences between mouse and human DPP4 receptors against MERS-CoV. However, further structural studies are needed to evaluate how DPP4 conformations affects MERS-CoV RBD binding and affinity.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Ahmed L Alaofi
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
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