Purification and Analysis of the Antigenic Properties of the Expressed Cucumber mosaic virus Coat Protein in Escherichia coli

Purification of expressed proteins is done to pursue different goals such as preparation of mono- and polyclonal antibodies, structural studies of the expressed proteins, identification of the amino acids and polypeptide sequences by chromatography which are generally costly and time- consuming. In this research, after expression of the coat protein (CP) gene of Cucumber mosaic virus (CMV) in Escherichia coli, purification of the expressed protein was done from polyacrylamide gel. To this aim, recombinant plasmid containing the CP gene was transformed into E. coli, induced by Isopropyl β-D-1-thiogalactopyranoside (IPTG) and followed by polyacrylamide gel electrophoresis of the extracted protein. The result showed that the yield of the recombinant protein was optimized to purification. After express the recombinant plasmid in large volume of LB, extracted protein was electrophoresed on the polyacrylamide gel. The location of the expressed protein was determined, and then the expected protein band was separated from the polyacrylamide gel before subjecting to protein purification. Next, the recombinant purified protein was injected to two rabbits to raise the antiserum. Titration of the prepared antiserum was performed by the use of an indirect ELISA. It appeared that the method applied in this study to purify the expressed protein was more efficient than other purification methods such as chromatography. Also, results of DIBA and rabbit immunization showed that the purified protein could be used as the antigen to prepare the antiserum and antibody for detection of the CMV isolates.