Optimization of parameters for expression and purification of G glycoprotein ectodomain of respiratory syncytial virus

Aim: G glycoprotein ectodomain (Ge) of BA genotype of group B respiratory syncytial virus was expressed and purified to achieve maximum yield of the protein. Materials & methods: We optimized different parameters like strains, temperature, inducer concentration and post induction time period for efficient protein expression in Escherichia coli. The protein was purified using affinity chromatography and confirmed by western blotting. Results: It was concluded that a 5-h induction with 0.75 mM isopropyl beta -D-1-thiogalactopyranoside at 37 degrees C in BL21(DE3) cells was the most favorable condition for maximal protein expression. The far-UV circular dichroism spectroscopy suggested that it is an alpha -helical protein. Conclusion: The purified Ge protein can be characterized by antigenic and biophysical methods in future studies, which will probably assist in vaccine development.