Optimizing expression and antibody preparation of recombinant Streptococcus mutans surface protein

Abstract

The soluble protein recombinant Streptococcus mutans surface protein (rPAc) was expressed in Escherichia coli (E.coli) after the optimization of inducing conditions. The antiserum against rPAc was obtained by immunizing mice with the purified rPAc. The soluble expression of rPAc in E. coli was further optimized by means of different culture conditions. Polyclonal antibody was made by immunizing mice with purified rPAc. Western blot and enzyme linked immunosorbent assay (ELISA) were carried out to identify the immunocompetence of the antibody. The highest soluble expression level of rPAc was obtained at Luria-Bertani (LB) medium (pH=7.2) when optical density (OD600nm) was 0.6 after being induced at 30 degrees C for 4 h and the concentration of isopropyl beta-D-1-thigalactopyranoside (IPTG) was 1.0mmol x L(-1). The titer of the mice antiserum against rPAc was about 1:6000 by ELISA analysis, and rPAc could be specifically recognized by Western blot analysis. This study proved that rPAc can be effectively expressed as a soluble form in E. coli, and the high specific polyclonal antibody of rPAc was proved to be prepared, which shed light on further research of DNA prime-protein boost inoculation.