Prokaryotic expression,purification and immune effect of CTB-FimA fusion protein
[Objective]To construct a recombinant plasmid pET-32a/CTB-FimA containing Porphyromonas gingivalis(Pg)fimbrial protein(FimA)and cholera toxin B subunit(CTB),to express and purify the fusion protein CTB-FimA and study its mucosal immune effect.[Method]The(Gly4Ser)3 linker peptide sequence was used to construct the pET-32a/CTB-FimA prokaryotic expression plasmid,which was transformed into E.coli BL21(DE3).The induction concentration and temperature of IPTG were determined,and the soluble protein was analyzed by SDS-PAGE.The target protein CTB-FimA was purified by affinity chromatography and gel filtration chromatography.BALB/c mice were immunized with the purified target protein by in-tranasal instillation to observe the mucosal immune effect.[Result]The recombinant expression plasmid pET-32a/CTB-Fi-mA was successfully constructed and confirmed by restriction enzyme digestion and sequencing.The optimal concentration of IPTG was 0.5 mmol/L,and the induction temperature was 23 ℃.The recombinant protein CTB-FimA was mainly expressed in soluble form.The molecular weight was 72.08 kDa predicated by the ProtParam tool of Expasy software,and the mean hydro-philicity was-0.313.Approximately 100 mg CTB-FimA protein was expressed per liter of fermentation broth.sIgA antibody titers in immunized BALB/c mice were significantly higher than those in the control group.[Conclusion]The recombinant ex-pression plasmid pET-32a/CTB-FimA was successfully constructed,and the soluble CTB-FimA recombinant protein was obtained.High-titer sIgA antibody was produced in BALB/c mice were immunized with CTB-fimA through nasal drip,which laid the foundation for the development of a vaccine against oral P.gingivalis infection.