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Cell Res. 2015 Nov;25(11):1237-49. doi: 10.1038/cr.2015.113. Epub 2015 Sep 22.

A humanized neutralizing antibody against MERS-CoV targeting the receptor-binding domain of the spike protein.

Li Y1, Wan Y1,2,3, Liu P1, Zhao J4,5, Lu G6, Qi J1, Wang Q3, Lu X7, Wu Y1, Liu W1, Zhang B2, Yuen KY8, Perlman S4, Gao GF1,2,9,10,11, Yan J1,2,3.

Author information

1
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Chinese Academy of Sciences, Beijing 100101, China.
2
School of Life Sciences, Anhui University, Hefei, Anhui 230039, China.
3
CAS Key Laboratory of Microbial and Metabolic engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
4
Departments of Microbiology and Pediatrics, University of Iowa, Iowa City, IA 52242, USA.
5
State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China.
6
State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan 610041, China.
7
Laboratory Animal Center, Chinese Center for Disease Control and Prevention (China CDC), Beijing 102206, China.
8
State Key Laboratory for Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
9
National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (China CDC), Beijing 102206, China.
10
China-Japan Joint Laboratory of Molecular Microbiology and Molecular Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
11
Office of Director-General, Chinese Center for Disease Control and Prevention (China CDC), Beijing 102206, China.

Abstract

The newly-emerging Middle East respiratory syndrome coronavirus (MERS-CoV) can cause severe and fatal acute respiratory disease in humans. Despite global efforts, the potential for an associated pandemic in the future cannot be excluded. The development of effective counter-measures is urgent. MERS-CoV-specific anti-viral drugs or vaccines are not yet available. Using the spike receptor-binding domain of MERS-CoV (MERS-RBD) to immunize mice, we identified two neutralizing monoclonal antibodies (mAbs) 4C2 and 2E6. Both mAbs potently bind to MERS-RBD and block virus entry in vitro with high efficacy. We further investigated their mechanisms of neutralization by crystallizing the complex between the Fab fragments and the RBD, and solved the structure of the 4C2 Fab/MERS-RBD complex. The structure showed that 4C2 recognizes an epitope that partially overlaps the receptor-binding footprint in MERS-RBD, thereby interfering with the virus/receptor interactions by both steric hindrance and interface-residue competition. 2E6 also blocks receptor binding, and competes with 4C2 for binding to MERS-RBD. Based on the structure, we further humanized 4C2 by preserving only the paratope residues and substituting the remaining amino acids with the counterparts from human immunoglobulins. The humanized 4C2 (4C2h) antibody sustained similar neutralizing activity and biochemical characteristics to the parental mouse antibody. Finally, we showed that 4C2h can significantly abate the virus titers in lungs of Ad5-hCD26-transduced mice infected with MERS-CoV, therefore representing a promising agent for prophylaxis and therapy in clinical settings.

PMID:
26391698
PMCID:
PMC4650419
DOI:
10.1038/cr.2015.113
[Indexed for MEDLINE]
Free PMC Article

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