The Study Of BEI Inactivation Effect On Poliovirus Sabin Strain And Effect Of Adjuvant On Inactivated Vaccine

As approaching of the aim of eradicating poliomyelitis all around the world, the circulating of vaccine-derived poliovirus(VDPV) and the occurring of vaccine-associated paralytic poliomyelitis(VAPP) became a big threaten to consolidate the goal of polio-free state. At the end of global polio eradication campaign, We should eradicate the wild-type polioviru as quickly as possible and use inactivated polio vaccine(IPV) to replace oral polio vaccine(OPV) to maintain the state of polio-free. WHO encouraged vaccine manufactures to develop IPV prepared with attenuated virus, Sabin strain, in consideration of biological safe factors during vaccine producing.This paper seeks to address Sabin II virus, to look for a better inactivator, which has little damage to the virus antigen comparing with formaldehyde; and to further explore the immune effect of adjuvant on Sabin IPV and to select optimal dose and adjuvant application significance.In Part 1 of the study, we observe the inactivation effect of BEI on Sabin strain type II poliovirus. Poliovirus was inactivated at different temperatures by four concentrations of BEI and formaldehyde. The content of D-antigen and live virus were determined by ELISA assays and virus infective titration respectively and carry out validated test of virus inactivation. After optimization, target virus can be completely inactivated by 0.002mol/L concentration of BEI at 37℃for 48 hour's incubation. The recovery of D-antigen is 90.6% and significant higher than 60.6% recovery with formaldehyde. According to the validated test, no live virus has been detected. BEI has less damage to D-antigen of Sabin strain type II poliovirus, indicating a greater protective effect to the viral protective antigen.In Part 2 of the study, four different doses of Sabin IPV were combined with adjuvant Al(OH)3 and Wistar rats were immunized. We detected serum antibody levels, specific IFN-y production as well as CD3/CD4/CD8 molecule expression differences. By micro-neutralization assay polio-specific neutralizing antibodies and GMT of Sabin strains was basically higher in the group of high dose of the vaccine comparing with the group of low dose of vaccine and the antibody levels were higher in adjuvant groups comparing with without adjuvant groups. The results of ELISPOT determination for the Sabin strains of polio virus-specific IFN-y indicated that the spots produced by adjuvant group were more than that produced by the group without adjuvant. FCM CD3/CD4/CD8 molecule expression showed that the difference,1-①experimental group CD3＋CD4＋/CD3＋CD8＋ratio is the maximum. In summary, Sabin IPV immune responses have enhanced by adding adjuvant; Experimental results indicated that typeⅠ30 DU/dose, typeⅡ16 DU/dose, type III 22.5 DU/dose could be a suitable dose.