In Silico Evaluation of a Mutant Toxic Shock Syndrome Toxin-1 (TSST-1) of Staphylococcus aureus as a Putative Vaccine Candidate

Introduction: The development of a vaccine against Staphylococcus aureus has proven to be much more difficult than expected. In this study, we considered and analyzed a mutant Toxic Shock Syndrome Toxin-1 (TSST-1) as a potential vaccine candidate. Methods: An NCBI sequence of TSST-1 was analyzed bioinformatically by online tools such as Ensemble and Pubmlst. The protein sequence of TSST-1 was similarly analysed by Expasy ProtParam, Phyre2 and Vaxign databases. The protein functional class was predicted by VICMpred database while the B- and T-cell epitopes were predicted by IEDB and BepiPred tools. The 3D structure was predicted by LOMETS, QMEAN, ProSA-web and ElliPro. The conservation of the epitopes was evaluated by ConSurf tool. Results: In silico analyses showed that this protein is present in high-prevalence sequence types of circulating clinical strains. It appears that TSST-1 has conserved liner and conformational B-cell epitopes. In addition, there are four potent of T-cell epitopes in this protein. Conclusion: This in silico data indicated that TSST-1 (and especially amino acid residues 81-221) is a promising vaccine target against S. aureus.