In vivo time-related evaluation of a therapeutic neutralization monoclonal antibody against lethal enterovirus 71 infection in a mouse model.

Zhiqun Li,Jun Zhang,Yixin Chen,Che Liu,Delei He,Tong Cheng,James Wai Kuo Shih,Longfa Xu,Qinjian Zhao,Lisheng Yang,Ningshao Xia,Ralph Tripp

doi:10.1371/journal.pone.0109391

Abstract

Enterovirus 71 (EV71) is a neurotropic virus capable of inducing severe neurological symptoms and death. No direct targeting antivirals are useful in the treatment of severe EV71 infection. Because of low toxicity and good specificity, monoclonal antibodies (MAb) are a potential candidate for the treatment of viral infections. Therefore, we developed an EV71-specific conformational MAb with high in vitro cross-neutralization activity to heterologous EV71 subgenotypes. The in vivo treatment experiment at different days post-infection indicated that a single treatment of MAb CT11F9 within day 3 post-infection fully protected mice from morbidity and mortality (0% PBS vs. 100% at 10 µg/g per body weight ***P<0.0001). Immunohistochemical and histological analysis confirmed that CT11F9 significantly prohibited EV71 VP1 expression in various tissues and prevented EV71-induced myonecrosis. Moreover, thrice-treatment at day 4, 5, 6 post-infection was associated with an increased survival rate (18.2% single vs. 50% thrice at 20 µg/g per body weight), and the mice recovered from limb paralysis. Competitive ELISA also confirmed that CT11F9-recognized epitopes were immunodominant in humans. In conclusion, MAb CT11F9 is an ideal candidate to be humanized and used in severe EV71 infection.

Highlights

Enterovirus 71 (EV71), belonging to the genus Enterovirus of the family Piconaviridae, is one of the major causative pathogens of hand, foot and mouth disease (HFMD)
We identified a series of nMAbs that could not react with whole purified EV71 Jiangsu or VP1, VP2 and VP3 proteins of EV71 by western blotting, which indicated that they recognized conformational epitopes of EV71 [13]
Severe necrotizing myositis was observed in the limb muscles of PBStreated mice compared to the normal morphology of CT11F9treated mice by hematoxylin and eosin (HE) staining (Fig. 2B). These results show that a single treatment of monoclonal antibodies (MAb) CT11F9 was able to fully protect mice from EV71-induced morbidity and mortality within day 3 postinfection, which was very close to the time when the mice began to present visible symptoms

Summary

Introduction

Enterovirus 71 (EV71), belonging to the genus Enterovirus of the family Piconaviridae, is one of the major causative pathogens of hand, foot and mouth disease (HFMD). We have successfully protected mice from lethal EV71 challenge with an EV71-VP2 targeted nMAb at 1 day post-infection [10] These data provide support for the effectiveness of neutralization antibody in the treatment of EV71 infection at early times of infection, there is a period of time in the host from the time of viral infection to the appearance of symptoms, which is a few days in a mouse model [11]. Identifying the suitable time to begin antibody therapy and whether antibody therapy is effective in mice with mild or severe complications will provide important information as to the treatment potential of MAb to EV71 infection and will provide guidance for clinical therapeutic usage in EV71 infection

Methods

Results

Conclusion