Research Article Design and evaluation of a diabody to improve protection against a potent scorpion neurotoxin

Diabodies are recombinant, dimeric, antibody- based molecules composed of two non-covalently associ- ated single-chain antibody fragments that bind to an anti- gen in a divalent manner. In an attempt to develop more effective therapeutic molecules against scorpion venoms, we designed a diabody derived from monoclonal antibody 9C2, which neutralizes the toxicity of scorpion neurotoxin AahI in mammals. The recombinant diabody produced in the periplasm of Escherichia coli was purified to homo- geneity in a single step by protein L-agarose affinity chro- matography. It was functional, and possessed a high bind-