GAPDH activity and immunogenicity of Staphylococcus aureus recombinant GapC protein

Abstract To characterize the Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity, immunogenicity and immunoprotection of Staphylococcus aureus ( S . aureus ) surface protein GapC, gapC gene of S . aureus was amplified from strain BMSA/855/23-1 by PCR, and was inserted into pQE-30 vector subsequently. The recombinant plasmid, designated as pQE/ gapC , was transformed into E . coli strain M15 (pREP4). The recombinant GapC fusion proein was successfully expressed in E . coli M15 induced with IPTG and its GAPDH activity was confirmed by GAPDH activity assay. Then, the recombinant GapC protein, inactivated S . aureus whole cell and placebo (PBS) were administrated to healthy rabbits respectively. The IgG antibody titers, concentration of IFN-γ and IL-4 cytokines in immunized rabbit sera were measured with Enzyme-Linked Immunosorbent Assay (ELISA). Finally, immunized rabbits were challenged with S . aureus strain Wood46 to evaluate the immunoprotection. The IgG antibody titers against GapC and whole cell in rabbit sera reached their peaks at day 28 after boost immunization (1:64 000). The concentrations of IL-4 and IFN-γ in GapC group rabbit sera increased significantly ( P P >0.05) compared with the placebo group. 4 rabbits in 5 of the protein immunized group were protected against challenge with 1×10 8 CFU S . aureus . The results above indicate that the expressed recombinant GapC protein have high GAPDH activity and immunogenicity, can also protect against S. aureus challenge to some extent. S. aureus GapC protein could be an attractive target for further genetic engineering vaccine.