Development Of A Subunit Vaccine Of Streptococcus Suis-haemophilus Parasuis

Swine streptococcal diseases is caused by Streptococcus suis(SS),which is characterized by meningitis,septicemia,arthritis.Glasser’s disease is caused by Haemophilus parasuis with the clinical symptoms like multiple serositis,arthritis,meningitis and pericarditis.Mixed infections often occurs in clinic,causing huge economic losses to pig industry.Vaccine is very useful in advocating the antibiotic-free breed industry.Taditional bacterial killed vaccine have poor cross protection for there are many serotypes in HPS and SS.But with the discovery of immunogenicity proteins,scientists are paying more attention in the subunit vaccine.It has been certificated that protein will keep its biological activity when being displayed on she surface of bacteria.The purpose of this study is to obtain an efficient,inexpensive and broad-spectrum SS-HPS binary subunit vaccine based on bacterial surface display,aiming to provide new conceptions for the de velopment of bacterial vaccines.In this study,surface display plasmids of pMD-INP-CdtB-OppA 、pMD-INP-AfuA-OppA2 、 pMD-INP-MRP 、pMD-INP-AfuA、pMD-INP-OppA2、pMD-INP-CdtB、pMD-INP-OppA was construted and transfered into E.coli BL21(DE3).And the AfuA-OppA2、CdtB-OppA、MRP、SLY、AfuA、CdtB、OppA2、OppA was displayed on the surface of E.coli BL21(DE3)certificated by subcellular components eisolation and immunoeletron microscopy.Bacterias were proportionally mixed after the concentration of proteins were quantified and the bacteria was inactived.The surface display subunit vaccine was produced after the bacteria liquid is emulsified with equal mass of ISA201 VG.Purified protein subunit vaccine and killed vaccine are also used as an comparation.The immunized mouses was challenged by absolute lethal dose of HPS serotype5 HN10 strain,HPS serotype13 ZD12 strain,SS serotype2 M126 strain,SS serotype9 GZ2 strain separately 14 days later after the second immunization.Results showed that the protection rates of surface display vaccine I with fusion antigen protein AfuA-OppA2,CdtB-OppA to the HPS serotype5 HN10 strain and HPS serotype13 ZD12 strain challenging was 80% and 80%,the protection rates of surface display vaccine Ⅱ with fusion antigen protein AfuA,OppA2,CdtB,OppA to the HPS serotype5 HN10 strain and HPS serotype13 ZD12 strain challenging was 90% and 60% indicating that fusing proteins together before bing displayed is feasible.Both of which is better than the protection of killed vaccine(80%、60%)and equal to the protection of purified protein subunit vaccine(90%、60%).In terms of the protective effect on the M126 and GZ2 challenging,the surface display subunit vaccine(50%、90%)is better than the killed vaccine(50%,60%)but lower than the purified protein subunit vaccine(100%,80%).The volum of cytokines and antibodies production activated by surface display subunit vaccine is equal to the effect of purified subunit vaccine.the easy fabrication process makes surface display subunit vaccine becoming more prosper in future’s application.