Immunogenicity Investigation of recombinant proteins (StxB) of Shigella dysenteriae type 1 in mice

Shigellosis is an acute intestinal infection from Shiga toxin and Shiga-like toxin, which is caused by Shigella and enterohemorrhagic Escherichia coli (EHEC) and entrotoxinogenic Escherichia coli (ETEC). The disease has a high prevalence rates in the world and is known as a bioterrorist agent. STxB is a part of Shiga toxin and have the property of immunogenicity. In this experimental study, the vector pET28a (+) containing the stxB gene was used and was transformed into E. coli BL21 DE3. The bacteria were grown on antibiotic medium and were confirmed with direct PCR, protein expression and SDS-PAGE gel. The recombinant protein purified by nickel column and was confirmed with SDS-PAGE gel and immunoblotting. The chitosan nanofibers containing STxB protein were synthesized by the electrospinning device. The Intranasal and injectable prescription of STxB protein and nanofibers containing STxB protein were performed in mice for four consecutive times and their Antibody titer were assessed. By ELISA, increased IgG antibody titers were observed in injectable and nasal view mode, which may not capture antigen by nasal epithelial cells in mice. By ELISA, The increase in IgG antibody titers was observed in injectable and intranasal states but not in naonnasal one, which may be due to the lack of antigen captured by nasal epithelial cells in mice. Immunized mice were able to tolerate five times of the Shiga toxin LD50 of E. coli O157: H7. The results of this study indicate that with nasal and injection prescribed of STxB protein, the immunized mice can tolerate E. coli O157: H7 Shiga toxin.