Recombinant Expression of Staphylococcus aureus Enterotoxin Type B as a Vaccine Candidate

Staphylococcus aureus is a gram-positive cocci that causes many diseases, such as food poisoning, risky shocks. Entrotoxins are the most important toxins of the bacteria. Among them, enterotoxin type B is the most common and important ones which is a super antigen. The aim of this study was the cloning and recombinant expression of seb gene in order to achieve a stable construct for the protein production and further use as a vaccine candidate in future investigations.
Subjects and seb gene was analyzed for rare codons and gene optimaztion was performed using bioinformatic softwares. Enzymatic digestion was performed to confirm the presence of the seb gene into pET28a() expression vector. Recombinant expression of SEB was induced by IPTG following cloning confirmation. Then, protein purification was done under non-denaturing conditions using a nickel chromatography column. Protein confirmation was performed by Western blotting analysis.
Codon adaptation index (CAI) of the native gene was 0.68, while the optimized sequence had a CAI of 0.82.Percentage of codon having high frequency distribution was improved to 57%. Restriction analysis confirmed the cloning of the seb gene into pET28a vector. The results showed that the cloning of seb gene in pET28a() vector was performed in an appropriate position between expected restriction sites. In addition, SEB had a good and significant expression after induction by IPTG. The total yield of purified protein was 22mg/L. Western blotting showed specific reactivity of recombinant protein with anti-his tag antibody.
Stable recombinant construct containing seb gene was constructed and appropriate recombinant expression of the protein was observed. So, this protein could be used in future studies as a vaccine candidate against SEB toxin of Staphylococcus aureus.