A fusion gene encoding two different insecticidal proteins of Bacillus thuringiensis

A chimeric fusion gene was constructed with the coding regions of insecticidal crystal protein (Cry1Ac) and vegetative insecticidal protein (Vip3Aa14) of Bacillus thuringiensis (Bt). Overexpression of the fusion gene in Escherichia coli resulted in the synthesis of a protein of similar to 140 kDa size, as revealed by SDS-PAGE analysis. Western hybridization analysis using polyclonal antisera raised against Cry1Ac showed the presence of a band corresponding to similar to 140 kDa. Stability of the fusion protein was studied by trypsin digestion. Insect bioassays of the fusion protein on three insect species viz., Helicoverpa armigera, Spodoptera litura and Plutella xylostella showed that the fusion protein retained the toxicity of Cry1Ac, but partially lost that of Vip3Aa14.