Toxic Peptides from the Mexican Scorpion : Chemical Structure and Evaluation of Recognition by Human Single-Chain Antibodies.

Alternative recombinant sources of antivenoms have been successfully generated. The application of such strategies requires the characterization of the venoms for the development of specific neutralizing molecules against the toxic components. Five toxic peptides to mammals from the Mexican scorpion were isolated by chromatographic procedures by means of gel filtration on Sephadex G-50, followed by ion-exchange columns on carboxy-methyl-cellulose (CMC) resins and finally purified by high-performance chromatography (HPLC) columns.

Neutralization of Centruroides tecomanus scorpion venom by the use of two human recombinant antibody fragments.

The first toxic component identified against mammals in the venom from Centruroides tecomanus scorpion from Colima, Mexico was Ct1a toxin, which was neutralized by human single chain variable fragment (scFv) RAS27. Venom characterization from these scorpions collected on the Pacific coast of Colima, enabled the identification of a second component of medical importance named Ct71 toxin. Amino acid sequence of Ct71 shares a high identity with Chui5 toxin from C.

Development of a human antibody fragment cross-neutralizing scorpion toxins.

Previously, it was demonstrated that from the single chain fragment variable (scFv) 3F it is possible to generate variants capable of neutralizing the Cn2 and Css2 toxins, as well as their respective venoms (Centruroides noxius and Centruroides suffusus). Despite this success, it has not been easy to modify the recognition of this family of scFvs toward other dangerous scorpion toxins. The analysis of toxin-scFv interactions and in vitro maturation strategies allowed us to propose a new maturation pathway for scFv 3F to broaden recognition toward other Mexican scorpion toxins.

Full Neutralization of Scorpion Venom by Combining Two Human Antibody Fragments.

A fundamental issue of the characterization of single-chain variable fragments (scFvs), capable of neutralizing scorpion toxins, is their cross-neutralizing ability. This aspect is very important in Mexico because all scorpions dangerous to humans belong to the genus, where toxin sequences show high identity. Among toxin-neutralizing antibodies that were generated in a previous study, scFv 10FG2 showed a broad cross-reactivity against several toxins, while the one of scFv LR is more limited.

Comparative assessment of the VH-VL and VL-VH orientations of single-chain variable fragments of scorpion toxin-neutralizing antibodies.

The present study evaluated the effect of the change in the orientation of the VH-VL variable domains to VL-VH on the physicochemical and functional properties of two scorpion toxin-neutralizing scFvs. The results showed that the level of expression of proteins obtained from the periplasm of E. coli is the factor mainly affected, either with an increase or decrease in the amount of protein recovered.