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Single-dose treatment with a humanized neutralizing antibody affords full protection of a human transgenic mouse model from lethal Middle East respiratory syndrome (MERS)-coronavirus infection - PubMed

Single-dose treatment with a humanized neutralizing antibody affords full protection of a human transgenic mouse model from lethal Middle East respiratory syndrome (MERS)-coronavirus infection

Hongjie Qiu et al. Antiviral Res. 2016 Aug.

Abstract

Middle East respiratory syndrome coronavirus (MERS-CoV) is continuously spreading and causing severe and fatal acute respiratory disease in humans. Prophylactic and therapeutic strategies are therefore urgently needed to control MERS-CoV infection. Here, we generated a humanized monoclonal antibody (mAb), designated hMS-1, which targeted the MERS-CoV receptor-binding domain (RBD) with high affinity. hMS-1 significantly blocked MERS-CoV RBD binding to its viral receptor, human dipeptidyl peptidase 4 (hDPP4), potently neutralized infection by a prototype MERS-CoV, and effectively cross-neutralized evolved MERS-CoV isolates through recognizing highly conserved RBD epitopes. Notably, single-dose treatment with hMS-1 completely protected hDPP4 transgenic (hDPP4-Tg) mice from lethal infection with MERS-CoV. Taken together, our data suggest that hMS-1 might be developed as an effective immunotherapeutic agent to treat patients infected with MERS-CoV, particularly in emergent cases.

Keywords: Humanized monoclonal antibody; Lethal infection; MERS-CoV; Protection; Receptor-binding domain; Treatment.

Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

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Conflict of interest statement

The authors declared no conflict of interest.

Figures

Fig. 1
Fig. 1

Analysis of hMS-1 expression. The expression of hMS-1 was resolved by reducing 12% SDS-PAGE (A) and non-reducing 8% SDS-PAGE (B) respectively, followed by Coomassie blue staining. Prestained protein molecular-weight markers (kDa) (Thermo Scientific) are indicated on the left of each panel.

Fig. 2
Fig. 2

hMS-1 blocks the binding between MERS-CoV RBD and the hDPP4 receptor. The blocking effect of hMS-1 on the cell-binding activity of MERS-CoV RBD was determined by flow cytometric analysis. (A) Blockage of Fc-fused MERS-CoV RBD protein binding to Huh-7 cells by 20 μg/ml hMS-1. Black line, Huh-7 cell control; purple line, binding of Fc-fused RBD to Huh-7 cells in the absence of antibody; blue line, irrelevant Trastuzumab mAb control; red line, MERS-CoV RBD binding of Huh-7 cells in the presence of hMS-1. (B) Flow cytometric analysis shows that hMS-1 inhibited the binding between the Fc-fused RBD protein and Huh-7 cells in a dose-dependent manner. The data are presented as the mean percentages of inhibition ± SEM (n = 3). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3
Fig. 3

Mapping of epitopes recognized by hMS-1 in MERS-CoV RBD. (A) Binding of hMS-1 to RBD mutant proteins as detected by ELISA. (B) Neutralizing activity of hMS-1 to pseudovirus mutants in a pseudovirus-based neutralization assay. Data are presented as the means ± SEM (n = 2). Protein and pseudovirus without mutations served as the wild type (WT) controls.

Fig. 4
Fig. 4

Therapeutic treatment with hMS-1 limits lung viral replication and alleviates lung injury induced by MERS-CoV infection. (A) Viral titers detected in the mouse lung at day 3 post-infection (n = 5). The data are expressed as the means ± SEM. **p < 0.01. The dotted line indicates the limit of detection. (B) Semiquantitative histopathological analysis of H&E-stained lung sections from mice sacrificed at day 3 post-infection (n = 5). The data are expressed as the means ± SEM. **p < 0.01. (C–J) Representative H&E-stained lung sections of hMS-1- and Trastuzumab-treated hDPP4 Tg mice, including locations on the trachea (D, H), vessel (E, I), and interstitial area (F, J) (scale bars, 100 μm for C, G; 50 μm for D–F, H–J).

Fig. 5
Fig. 5

Single-dose treatment of hMS-1 fully protects hDPP4 transgenic mice from lethal MERS-CoV infection. The hDPP4 transgenic mice were administered a single-dose of hMS-1 or the irrelevant Trastuzumab 24 h after lethal infection of MERS-CoV and then monitored for 23 days. (A) Body weight changes of hMS-1- and Trastuzumab-treated mice. Results are expressed as the means ± SEM (n = 6). (B) Survival rate (%) of hMS-1- and Trastuzumab-treated mice (n = 6). **p < 0.01.

Supplementary Fig. 1
Supplementary Fig. 1

Amino acid differences among the RBDs of the S proteins of natural MERS-CoV isolates. A total of 278 full-length spike proteins of MERS-CoV isolates were aligned. Different amino acid residues among the RBDs of natural isolates are listed. Amino acids in the top row show consensus residues and the numbers of the corresponding amino acid residues are indicated. Parenthesized numbers on the left indicate the counts of isolates with identical sequences in the amino acid region. The residues of the MERS-CoV RBD and receptor-binding motif (RBM) are illustrated at the top of the figure.

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