Development of Human-Like scFv-Fc Neutralizing Botulinum Neurotoxin E.

Sebastian Miethe (1) , Christine Rasetti-Escargueil (2) , Arnaud Avril (3) , Yvonne Liu (2) , Siham Chahboun (3) , Hannu Korkeala (4) , Christelle Mazuet (5) , Michel-Robert Popoff (5) , Thibaut Pelat (3) , Philippe Thullier (3) , Dorothea Sesardic (2) , Michael Hust (1)

1 Abteilung Biotechnologie
2 Division of Bacteriology [UK]
3 Unité de biotechnologie des anticorps et des toxines
4 Department of Food Hygiene and Environmental Health [Helsinki]
5 Bactéries anaérobies et Toxines

Botulinum neurotoxins (BoNTs) are considered to be the most toxic substances known on earth and are responsible for human botulism, a life-threatening disease characterized by flaccid muscle paralysis that occurs naturally by food-poisoning or colonization of the gastrointestinal tract by BoNT-producing clostridia. BoNTs have been classified as category A agent by the Centers of Disease Control and Prevention (CDC) and are listed among the six agents with the highest risk to be used as bioweapons. Neutralizing antibodies are required for the development of effective anti-botulism therapies to deal with the potential risk of exposure. In this study, a macaque (Macaca fascicularis) was immunized with recombinant light chain of BoNT/E3 and an immune phage display library was constructed. After a multi-step panning, several antibody fragments (scFv, single chain fragment variable) with nanomolar affinities were isolated, that inhibited the endopeptidase activity of pure BoNT/E3 in vitro by targeting its light chain. Furthermore, three scFv were confirmed to neutralize BoNT/E3 induced paralysis in an ex vivo mouse phrenic nerve-hemidiaphragm assay. The most effective neutralization (20LD50/mL, BoNT/E3) was observed with scFv ELC18, with a minimum neutralizing concentration at 0.3 nM. Furthermore, ELC18 was highly effective in vivo when administered as an scFv-Fc construct. Complete protection of 1LD50 BoNT/E3 was observed with 1.6 ng/dose in the mouse flaccid paralysis assay. These scFv-Fcs antibodies are the first recombinant antibodies neutralizing BoNT/E by targeting its light chain. The human-like nature of the isolated antibodies is predicting a good tolerance for further clinical development.

Domains: Bacteriology

Sebastian Miethe, Christine Rasetti-Escargueil, Arnaud Avril, Yvonne Liu, Siham Chahboun, et al.. Development of Human-Like scFv-Fc Neutralizing Botulinum Neurotoxin E.. PLoS ONE, 2015, 10 (10), pp.e0139905. ⟨10.1371/journal.pone.0139905⟩. ⟨pasteur-01325687⟩