Cloning and Expression of the E Protein from West Nile Virus

West Nile virus (WNV), genus Flavivirus, family Flaviviridae, is an old world arbovirus, transmitted mainly by infected mosquitoes. It was described as serious disease with a strong influence on public health. In this study, the cDNA template of E gene was amplified by PCR and cloned into pMD18-T simple vector. After double digestion with restriction enzyme (BamH1 and SAL1) and verified by sequencing. The gene was then inserted into the plasmid pET-32a (+), transformed into Escherichia coli BL21 (DE3) and expressed after induction by IPTG at the final concentration of 1.0 mmol. L-1, at 28 for 4 hours. Then the expression product was identified by SDS-PAGE. The recombinant E protein was purified and used as antigen in immunization of rabbit to evaluate its ability to stimulate immune responses. The results showed that the molecular mass of expression protein was 73 kDa and Western blotting analysis indicated that the antigenicity of the protein was specific.