Expression of Salmonella typhimurium and Escherichia coli flagellin protein and its functional characterization as an adjuvant

Abstract

Background: Flagellin is the major structural protein monomer of bacterial flagella. Flagellin through binding to its receptor and activation of antigen presenting cells stimulates the innate and adaptive immune responses. Flagellin is used as an effective systemic or mucosal adjuvant to stimulate the immune system. Recently, the therapeutic and protective role of flagellin in some infectious diseases and cancers has been investigated. In this study, we cloned the fliC genes from Salmonella typhimurium and Escherichia coli into pET-28a vector and investigated their expression in the prokaryotic system.

Methods: The fliC genes of S. typhimurium and E. coli were amplified by PCR with a specific oligonucleotide primer set. thse were cloned into the pET-28a vector and the recombinant pET-28a-fliC plasmids were successfully transformed into the E. coli strain BL-21(DE3). The expression of flagellin proteins in the prokaryotic cells were evaluated. Finally, Transcription of TNF-α mRNA was confirmed using Real-time PCR.

Results: The expression of proteins in the prokaryotic cells were approved by SDS-PAGE and western blotting method. Further, the functional characterization of flagellin proteins were evaluated using their ability to induce increased m-RNA expression of pro-inflammatory cytokine.

Conclusions: The flagellin proteins were expressed in the prokaryotic system. These proteins can be used to link target antigens as an effective adjuvant for future DNA vaccine studies. Purified recombinant proteins in this study can also be used for therapeutic and prophylactic purposes.

Keywords: Adjuvant; Escherichia coli; Salmonella typhimurium; fliC gene; pET-28a.