Cloning and Expression of Nucleocapsid Protein Gene of Equine Arteritis Virus in E.coli

The gene of nucleocapsid protein of Equine arteritis virus was amplified from PMD-18-T plasmid with equine arteritis virus ORF7 sequence by PCR. The PCR product was sequenced as well as purified and digested with EcoR I and Xho I, then directly cloned into the prokaryotic vector pET32a. Consequently the recombinant plasmid was constructed, designateds pET32a-N. PET32a-N was transformed into the host cell BL21(DE3) and the expression procedure was optimized including cultivated temperature, optional induction concentration and time of IPTG. The result indicated that the nucleocapsid protein can be expressed efficiently with 0.8mmol/L IPTG and 4 hour induction. The resulting Trx-N recombinant fusion protein was identified to be consisted of 34 kDa protein by SDS-PAGE and western blotting analysis. It indicated that the recombinant fusion protein could be used as antigen of diagnostic assay for detecting antibodies.