Journal Article

A Novel Strategy for Development of Recombinant Antitoxin Therapeutics Tested in a Mouse Botulism Model

Baldwin, Karen, Mukherjee, Jean, Webb, Robert P., Smith, Leonard A., Bedenice, Daniela, Wright, Patrick M., Tremblay, Jacqueline M., Tzipori, Saul, Leysath, Clinton E., Ofori, Kwasi, Feng, Xiaochuan, Shoemaker, Charles B.

2012

Overview

Antitoxins are needed that can be produced economically with improved safety and shelf life compared to conventional antisera-based therapeutics. Here we report a practical strategy for development of simple antitoxin therapeutics with substantial advantages over currently available treatments. The therapeutic strategy employs a single recombinant 'targeting agent' that binds a toxin at two unique sites and a 'clearing Ab' that binds two epitopes present on each targeting agent. Co-administration of the targeting agent and the clearing Ab results in decoration of the toxin with up to four Abs to promote accelerated clearance. The therapeutic strategy was applied to two Botulinum neurotoxin (BoNT) serotypes and protected mice from lethality in two different intoxication models with an efficacy equivalent to conventional antitoxin serum. Targeting agents were a single recombinant protein consisting of a heterodimer of two camelid anti-BoNT heavy-chain-only Ab V(H) (VHH) binding domains and two E-tag epitopes. The clearing mAb was an anti-E-tag mAb. By comparing the in vivo efficacy of treatments that employed neutralizing vs. non-neutralizing agents or the presence vs. absence of clearing Ab permitted unprecedented insight into the roles of toxin neutralization and clearance in antitoxin efficacy. Surprisingly, when a post-intoxication treatment model was used, a toxin-neutralizing heterodimer agent fully protected mice from intoxication even in the absence of clearing Ab. Thus a single, easy-to-produce recombinant protein was as efficacious as polyclonal antiserum in a clinically-relevant mouse model of botulism. This strategy should have widespread application in antitoxin development and other therapies in which neutralization and/or accelerated clearance of a serum biomolecule can offer therapeutic benefit.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Animal models / Animals / Antibody Affinity / Antigenic determinants / Antigens / Antisera / Antitoxins / Antitoxins - biosynthesis / Antitoxins - metabolism / Antitoxins - therapeutic use / Biological products / Biology / Botulinum Antitoxin - biosynthesis / Botulinum Antitoxin - metabolism / Botulinum Antitoxin - therapeutic use / Botulinum toxin / Botulism / Botulism - immunology / Botulism - mortality / Botulism - pathology / Botulism - therapy / Clearing / Clostridium botulinum / Comparative analysis / Development strategies / Disease Models, Animal / Drug development / Drug Discovery - methods / Drugs, Investigational - metabolism / Drugs, Investigational - therapeutic use / Economic models / Effectiveness / Epitopes / Female / Food contamination / Food safety / Health aspects / Identification / Immunoglobulins / Immunotherapy - methods / Immunotherapy - trends / Infectious diseases / Intoxication / Lama pacos / Lethality / Medical research / Medicine / Mice / Models, Biological / Monoclonal antibodies / Natural products / Nematodes / Neurotoxins / Neutralization / Neutralizing / Protein Multimerization - physiology / Recombinant proteins / Recombinant Proteins - biosynthesis / Recombinant Proteins - metabolism / Recombinant Proteins - therapeutic use / Serotypes / Shelf life / Strategy / Survival Analysis / Toxins / Treatment Outcome / Trends / Veterinary colleges / Veterinary medicine / Water-borne diseases / Waterborne diseases