• In silico designing of a novel epitope-based candidate vaccine targeting pneumococcal surface protein C (PspC)
  • Mona Shafaghi,1 Zohreh Bahadori,2,*
    1. 1 Department of Medical Biotechnology, Faculty of Medicine, Semnan University of Medical Sciences, Semnan, Iran. 2 Department of Bacteriology, Pasteur Institute of Iran, Tehran, Iran.
    2. 1 Department of Medical Biotechnology, Faculty of Medicine, Semnan University of Medical Sciences, Semnan, Iran. 2 Department of Bacteriology, Pasteur Institute of Iran, Tehran, Iran.


  • Introduction: Streptococcus pneumoniae is the leading reason for invasive diseases including pneumonia and meningitis, and also secondary infections following viral respiratory diseases such as flu and COVID-19. Currently, serotype-dependent vaccines, which have several insufficiency and limitations, are the only way to prevent pneumococcal infections. Hence, it is plain to need an alternative effective strategy for prevention of this organism. Protein-based vaccine involving conserved pneumococcal protein with different roles in virulence could provide an eligible alternative to existing vaccines. Pneumococcal surface protein C (PspC), an immunogenic and conserved surface protein, can produce different levels of protection against pneumococcal strains.
  • Methods: In this study, the protein PspC was taken to account to predict B-cell and helper T-cell epitopes using immunoinformatics tools. The epitope-rich regions were chosen and linked together with suitable linker to build the final construct. The evaluation of physicochemical properties, antigenicity, and toxicity, prediction of 3D model and conformational B cell epitopes in the final model, molecular docking of the final construct with HLA receptor, and simulation of immune response were carried out by computational tools.
  • Results: The in silico results showed that the developed construct was stable, antigenic, soluble, and non-toxic. The 3D structure was constructed and refined, and the R-plot, ProSA Z-score, and ERRAT score verified the quality of the model. The docking analysis indicated favorable interactions between HLA and the designed construct. Finally, codon adaptation was conducted to enhance the expression of the designed vaccine in E. coli followed by in silico cloning in the pET28a(+)vector. The computational outcomes revealed that the suggested vaccine could pass the evaluations with satisfactory scores and could be deemed to have the potential to induce strong immune responses.
  • Conclusion: For the first time this work presents a novel vaccine containing the immunodominant epitope regions of PspC antigen. The computational outcomes revealed acceptable results, nevertheless, in vitro and in vivo examinations should be performed to prove the potency of the candidate vaccine.
  • Keywords: Pneumococcal surface protein C (PspC), Immunoinformatics, Epitope-based candidate vaccine.