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

• Published in: Clinical & developmental immunology 2013-01, Vol.2013 (2013), p.1-8
• Main Authors: Cheng, Xunjia, Duesbery, Nicholas S., Zhu, Jin, Chen, Ximin, Ding, Guipeng, Cao, Brian
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antibodies, Neutralizing - genetics; Antibodies, Neutralizing - immunology; Antibodies, Neutralizing - pharmacology; Antibody Affinity; Antibody Specificity; Antigens, Bacterial - immunology; Bacillus anthracis - drug effects; Bacillus anthracis - growth & development; Bacillus anthracis - immunology; Bacterial Toxins - antagonists & inhibitors; Bacterial Toxins - immunology; Base Sequence; Cell Line; Escherichia coli - genetics; Gene Expression; Immunoglobulin Fab Fragments - genetics; Immunoglobulin Fab Fragments - immunology; Immunoglobulin Fab Fragments - pharmacology; Macrophages - drug effects; Macrophages - immunology; Macrophages - microbiology; Mice; Molecular Sequence Data; Protein Engineering; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - immunology; Recombinant Fusion Proteins - pharmacology
• ISSN: 2314-8861; 1740-2522; 2314-7156; 1740-2530
• DOI: 10.1155/2013/475809

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 3.46×107 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.