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Clinical and Developmental Immunology
Volume 2013 (2013), Article ID 475809, 8 pages
http://dx.doi.org/10.1155/2013/475809
Research Article

A Human/Murine Chimeric Fab Antibody Neutralizes Anthrax Lethal Toxin In Vitro

1Department of Pathology, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, China
2Huadong Medical Institute of Biotechniques, 293 East Zhongshan Road, Nanjing 210002, China
3Laboratory of Cancer and Developmental Cell Biology, Van Andel Research Institute, 333 Bostwick Avenue, Grand Rapids, MI 49503, USA
4Department of Medical Microbiology and Parasitology, Shanghai Medical College of Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
5Laboratory of Antibody Technology, Van Andel Research Institute, 333 Bostwick Avenue, Grand Rapids, MI 49503, USA

Received 10 March 2013; Revised 12 May 2013; Accepted 13 May 2013

Academic Editor: Roberto Burioni

Copyright © 2013 Guipeng Ding et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Human anthrax infection caused by exposure to Bacillus anthracis cannot always be treated by antibiotics. This is mostly because of the effect of the remaining anthrax toxin in the body. Lethal factor (LF) is a component of lethal toxin (LeTx), which is the major virulence of anthrax toxin. A murine IgG monoclonal antibody (mAb) against LF with blocking activity (coded LF8) was produced in a previous study. In this report, a human/murine chimeric Fab mAb (coded LF8-Fab) was developed from LF8 by inserting murine variable regions into human constant regions using antibody engineering to reduce the incompatibility of the murine antibody for human use. The LF8-Fab expressed in Escherichia coli could specifically identify LF with an affinity of  L/mol and could neutralize LeTx with an EC50 of 85 μg/mL. Even after LeTx challenge at various time points, the LF8-Fab demonstrated protection of J774A.1 cells in vitro. The results suggest that the LF8-Fab might be further characterized and potentially be used for clinical applications against anthrax infection.