Objective: To co-express antigen and antibody in E.coli periplasm in which the antigen and antibody will fold correctly and bind to each other.
Methods: Human IL-1β gene and mouse anti-human IL-1β single chain variable fragment (anti-hIL-1β scFv) were inserted into the down stream from the NlpA and pelB leading peptides of pBFD vector respectively. The recombinant plasmid was named pBFD-Ab-Ag. The E.coli DH5α transformed with pBFD-Ab-Ag was induced by IPTG to co-express antigen and antibody. After the outer membrane of E.coli DH5α was broken (spheroplast formation), the bacteria were incubated with mouse anti-hIL-1β antibody labeled by FITC. The co-expression and interaction of antigen and antibody was analyzed by flow cytometry (FCM) based on fluorescence signal intensity.
Results: The FCM detection showed the strong signal in E.coli DH5α transformed with pBFD-Ab-Ag and the positive rate was significantly improved.
Conclusion: The results showed that the antigen and antibody can fold and bind to each other efficiently in E.coli periplasm. The system can make antibody screening process easier and also provide a novel method for protein-protein interaction.