In order to investigate the cloning,expression and immunological activity analysis E2 gene of classical swine fever virus (CSFV) isolates from Sichuan. The CSFV total RNA of Sichuan strain was extracted from infected PK-15 cells. The objective E 2 gene was cloned by RT-PCR and directionally cloned into prokaryotic expression vector. The expressing plasmids were transformed into E.coli Rosetta-gami-TM(DE3) plysS. The recombinant bacteria were induced expression by IPTG. The expressed proteins were analyzed by SDS-PAGE and Western blotting. The results indicated that the objective E 2 gene was obtained and contains E2 protein complete codon DNA sequence (CDS), which have 1119 bp，encoding 373 amino acid. The recombinant expression plasmids were successfully constructed of complete CDS and N terminal major antigen gene of CSFV E2 protein,which named pET-E2(pe) and pET-mE2(pe). The recombinant bacteria could express the target fusion proteins which are about 45.32 ku and 28.49 ku by SDS-PAGE detection. The expression of E2 (pe),mE2 (pe) fusion proteins could be recognized by CSFV-positive sera,and had good immunological reaction activity. The research obtained the CSFV E2 gene of Sichuan strain. The E2 (pe)，mE2 (pe) fusion proteins were expressed and have biological activity.
