Functional EL-HN Fragment as a Potent Candidate Vaccine for the Prevention of Botulinum Neurotoxin Serotype E.

Zhen Li,Xiao Tan,Qing Xu,Jiansheng Lu,Zhixin Yang,Yunzhou Yu,Rong Wang

doi:10.3390/toxins14020135

Abstract

Clostridium botulinum produces botulinum neurotoxin (BoNT), which is the most toxic known protein and the causative agent of human botulism. BoNTs have similar structures and functions, comprising three functional domains: catalytic domain (L), translocation domain (HN), and receptor-binding domain (Hc). In the present study, BoNT/E was selected as a model toxin to further explore the immunological significance of each domain. The EL-HN fragment (L and HN domains of BoNT/E) retained the enzymatic activity without in vivo neurotoxicity. Extensive investigations showed EL-HN functional fragment had the highest protective efficacy and contained some functional neutralizing epitopes. Further experiments demonstrated the EL-HN provided a superior protective effect compared with the EHc or EHc and EL-HN combination. Thus, the EL-HN played an important role in immune protection against BoNT/E and could provide an excellent platform for the design of botulinum vaccines and neutralizing antibodies. The EL-HN has the potential to replace EHc or toxoid as the optimal immunogen for the botulinum vaccine.

Highlights

Botulinum neurotoxin (BoNT) is a neurotoxin produced by Clostridium botulinum in an anaerobic environment [1,2]
Our results showed that the recombinant EL-HN fragment (L and HN domains of BoNT/E), which was described previously by Shone et al [19], has native neurotoxin activity and could generate powerful neutralizing antibodies, playing an important role in immune protection against BoNT/E
These recombinant functional fragments were expressed in E. coli (BL21), and the purified proteins were identified by both their molecular weight and reaction with specific antibodies to BoNT/E in immunoblots

Summary

Introduction

Botulinum neurotoxin (BoNT) is a neurotoxin produced by Clostridium botulinum in an anaerobic environment [1,2]. BoNT is the most toxic protein among bacteria, animals, plants, and chemical substances reported to date. BoNTs are classified immunologically into distinct serotypes: from BoNT/A to BoNT/G. Botulinum neurotoxin serotypes A, B, E, and F cause botulism in humans. Botulinum neurotoxin has been classified as an A-class biological warfare agent and an important bioterrorism agent because of its high toxicity and relative ease of production and transportation [3,4]. Novel types of BoNTs (e.g., BoNT/HA and BoNT/X) have been identified in recent years [1,5]

Methods

Results

Discussion

Conclusion