Scorpion long-chain insect neurotoxins have important potential application value in agricultural pest control. The difficulty of obtaining natural toxins is the major obstacle preventing analyses of their insecticidal activity against more agricultural insect pests. Here we cloned the insect neurotoxin Bj alpha IT gene into the pET32 expression vector and expressed the resulting thioredoxin (Trx)-Bj alpha IT fusion protein in Escherichia coli. Soluble Trx-Bj alpha IT was expressed at a high level when induced at 18 degrees C with 0.1 mM isopropyl eta-D-1-thiogalactopyranoside, and it was purified by Ni2+-nitriloacetic acid affinity chromatography. After cleaving the Trx tag with recombinant enterokinase, the digestion products were purified by CM Sepharose FF ion-exchange chromatography, and 1.5 mg of purified recombinant BjaIT (rBj alpha IT) was obtained from 100 ml of induced bacterial cells. Injecting rBj alpha IT induced obvious neurotoxic symptoms and led to death in locust (Locusta migratoria) larvae. Dietary toxicity was not observed in locusts. The results demonstrate that active rBj alpha IT could be obtained efficiently from an E. coli expression system, which is helpful for determining its insecticidal activity against agricultural insect pests. (C) 2017 Elsevier Inc. All rights reserved.