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

Document Type : Original Article


1 PhD Student in Nanobiotechnology.Biology Research Center, Faculty of Basic Science, Imam Hossein University, Tehran, Iran.

2 Assistant Professor of Biology.Department of Biology, Faculty of Basic Science, Imam Hossein University, Tehran, Iran.

3 MSc Student in Cellular and Molecular biology.Biology Research Center, Faculty of Basic Science, Imam Hossein University, Tehran, Iran.


Background and Objective: 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 Methods: 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.
Results: 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.
Conclusion: 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.      


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