Expression and purification of circumsporozoite protein from Plasmodium falcipanan FCC1/HN strain and its binding activity in hepatocyte
Objective To amplify circumsporozoite protein gene from genome DNA of Plasmodium falci-parum FCC1/HN strain, to express and purify CSP in prokaryotic vector pET-32c, with evaluation of its immunoge-necity and binding activity to hepatic cell. Methods A pair of primers was designed according to cDNA sequence of CSP from Plasmodium falciparum strain 3D7, the CSP gene amplified by PCR was cloned into the vector pGEM-T and proved by DNA sequencing. Then the CSP gene was subcloned into procaryotic expression vector pET-32c and expressed by induction with IPTG. The recombinant CSP was purified with Ni2+ chelating HiTrap HP column in denatured condition. Its immunoresponse was evaluated by Western blot, and its binding activity in different tissue sections was detected by immunohistochemistry (IHC). Results The CSP gene was successfully amplified from genome DNA of Plasmodium falciparum strain FCC1/HN. An approximate Mr 62×103 fusion protein was expressed in E. coli and prepared with Ni2+ column purification. The result of Western blot showed that rCSP was recognized by Malaria patient serum. The results of IHC showed that rCSP could bind specifically to the hepa-tocytes. Conclusion The purified rCSP has strong immunoresponse and binding activity in hepatocytes, which indicates that rCSP has a potential value as a targeting molecule for hepatic gene delivery.