Expression of recombinant Hc domain of Clostridium botulinum neurotoxin A in E. coli and its purification as a vaccine candidate against botulism

Botulism is a lethal disease which is caused by the one of the neurotoxins of the 7 types of Clostridium botulinum. The carboxylic domain of the heavy chain of Clostridium botulinum type A neurotoxin (BoNT/A-Hc), is highly capable of activating immune system and is used for production of a vaccine against botulism. The aim of this study was to express and produce soluble form of BoNT/A-Hc in recombinant E. coli.

Hc part of BoNT/A was subcloned in pET28a vector and clone was expressed in E. coli BL21 (DE3). Then the best recombinant clones were selected based on three main factors: expression, growth and plasmid stability. Then protein expression was evaluated in LB and M9 media and the protein was purified by resin column chromatography.

In flask culture, under optimal conditions of bacterial culture yielded 52mg of BoNT/A-Hc soluble protein from each liter of culture medium.

According to the results of this study, selection of suitable strains on the basis of important growth indices of the bacteria, expression of recombinant protein and plasmid stability can lead to in increased efficiency of the recombinant protein production.