Generation of a Broadly Cross-Neutralizing Antibody Fragment against Several Mexican Scorpion Venoms

Lidia Riaño-Umbarila,Baltazar Becerril,Guillermo Fernández-Taboada,Lourival Possani,Ilse Gómez-Ramírez,Timoteo Olamendi-Portugal,Luis Ledezma-Candanoza,Everardo Rodríguez-Rodríguez

doi:10.3390/toxins11010032

Abstract

The recombinant antibody fragments generated against the toxic components of scorpion venoms are considered a promising alternative for obtaining new antivenoms for therapy. Using directed evolution and site-directed mutagenesis, it was possible to generate a human single-chain antibody fragment with a broad cross-reactivity that retained recognition for its original antigen. This variant is the first antibody fragment that neutralizes the effect of an estimated 13 neurotoxins present in the venom of nine species of Mexican scorpions. This single antibody fragment showed the properties of a polyvalent antivenom. These results represent a significant advance in the development of new antivenoms against scorpion stings, since the number of components would be minimized due to their broad cross-neutralization capacity, while at the same time bypassing animal immunization.

Highlights

In Mexico, scorpion stings represent an important public health problem due to the existence of a great diversity of medically important species
In Vitro Maturation of Antibody Fragments scFv ER-1 [22], a variant derived from scFv C1 (Table 2) which showed a good level of recognition against toxin Cll2 [8] and Ct1a [24] (Table 1), was modified in order to improve its recognition toward these toxins
The comparison of the respective Biacore sensorgrams for the interaction between scFvs and toxins indicated that none of the generated variants showed any improvement as compared to scFv 10F, which was selected in the second round of biopanning (Figure 1, panels A and B)

Summary

Introduction

In Mexico, scorpion stings represent an important public health problem due to the existence of a great diversity of medically important species. We have confirmed the toxicity of a total of 14 species of scorpions [1] (six of them formally unknown as dangerous to humans). The deep characterization of the venom of some of these species enabled the identification of toxic components that correspond to a few peptides of only 66 aa [2,3]. These peptides are defined as neurotoxins, because they act on the sodium channels of excitable cells modulating their gate function, and alter the transmission of nerve impulses and end up triggering serious symptoms of intoxication such as asphyxia, partial paralysis, and cardiopulmonary shock.

Methods

Results

Conclusion