Expression Of Poliovirus Sabin2 Structural Proteins In Insect Cell Using The Baculovirus Expression System

Poliomyelitis is a highly infectious disease caused by any one of three types of poliovirus, type 1, type 2 or type 3. The disease has no specific treatment but can be prevented through vaccination. Incidence of poliomyelitis has been reduced greatly by oral poliovirus vaccine. However, for risks of vaccine associated paralytic poliomyelitis and vaccine-derived poliovirus, the use of oral poliovirus vaccine will have to be stopped to eradicate poliomyelitis. Following elimination of wild-type polioviruses, production of conventional inactivated poliovirus vaccine will be administered strictly. But antigenicity and immunogenicity of Sabin inactivated poliovirus vaccine are different from that of conventional inactivated poliovirus vaccine. New poliovirus vaccine is needed to be researched. Virus like particles of poliovirus may be one promising type of poliovirus vaccine.The Bac-to-Bac baculovirus expression system was employed to express the structural proteins of poliovirus Sabin2 strain in the research. The major antigen sites of poliovirus are in VP1 protein, and the P1 precursor is processed by the viral protease 3C or 3CD into structural proteins VP0, VP3 and VP1. So first, VP1, P1, 3C and 3CD genes were synthesized by RT-PCR, then, we constructed 4 recombinant baculoviruses: rBac-VP1, rBac-P1, rBac-3C and rBac-3CD, last, rBac-VP1, rBac-P1 and rBac-3C or rBac-P1and rBac-3CD infected Sf9 cells to express proteins. Result: Obvious cytopathic effect (CPE) was observed in the Sf9 cells transfected by the recombinant baculovirus expressing plasmid of gene VP1, P1, 3C or 3CD. Expression of VP1 protein was identified by indirect fluorescence assay (IFA) and Western-Blot assay, furthermore, the protein possessed antigenicity. Multimetric protein was yielded in Sf9 cells ether infected by rBac-P1 and rBac-3C or rBac-P1and rBac-3CD, which indicated virus-like particles (VLPs) assembly.Poliovirus Sabin2 structural proteins were successfully synthesized in insect cells by baculovirus expression system,which laid the foundation for study on new poliovirus vaccines.