Production and Immunological Evaluation of Epitope-based Preventative Pneumococcal Candidate Vaccine Comprising Immunodominant Epitopes from PspA, CbpA, PhtD and PiuA Antigens.

BACKGROUND

Streptococcus pneumoniae is the leading cause of pneumonia, mostly in children less than five years and elderly people. Although the Pneumoniae Polysaccharide Vaccine (PPV) and Pneumonia Conjugate Vaccines (PCV) are the efficient pneumococcal vaccine in adults and children, the serotype replacement of S. pneumoniae strains causes the reduction in the efficacy of PPV and PCV vaccines. Epitope-based vaccines are a promising alternative to the present capsular antigen vaccines.

METHODS

In this study, we evaluated cellular and humoral immune responses induced by our novel designed multi-epitope vaccine in BALB/c mice. CD8+ Cytolytic T Lymphocytes (CTLs) epitopes were selected from PspA and CbpA antigens, and CD4+ Helper T Lymphocytes (HTLs) epitopes were chosen from PhtD and PiuA antigens. PorB, the TLR2 agonist, as an adjuvant, was employed to increase the immunogenicity of the vaccine.

RESULTS AND CONCLUSION

The high levels of specific anti-peptide vaccine IgG and an increase in the level of IgG2 in the vaccinated group demonstrated our vaccine could elicit robust antibody production. The significant increase in IFN-γ, IL-2, TNF-α, IL-4, IL-6, and decrease in IL-10 showed that the designed vaccine could be proposed as the efficient preventative pneumococcal vaccine in the mouse model.