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.

Production and Preliminary In Vivo Evaluations of a Novel in silico-designed L2-based Potential HPV Vaccine.

BACKGROUND: L2-based Human Papillomavirus (HPV) prophylactic vaccines, containing epitopes from HPV minor capsid proteins, are under investigation as second-generation HPV vaccines. No such vaccine has passed clinical trials yet, mainly due to the low immunogenicity of peptide vaccines; so efforts are being continued. A candidate vaccine composed of two HPV16 L2 epitopes, flagellin and a Toll-Like Receptor (TLR) 4 agonist (RS09) as adjuvants, and two universal T-helper epitopes was designed in silico in our previous researches. METHODS: The designed vaccine construct was expressed in E. coli BL21 (DE3) and purified through metal affinity chromatography. Following mice vaccination, blood samples underwent ELISA and flow cytometry analyses for the detection of IgG and seven Th1 and Th2 cytokines. RESULTS: Following immunization, Th1 (IFN-γ, IL-2) and Th2 (IL-4, IL-5, IL-10) type cytokines, as well as IgG, were induced significantly compared with the PBS group. Significant increases in IFN-γ, IL-2, and IL-5 levels were observed in the vaccinated group versus Freund's adjuvant group. CONCLUSION: The obtained cytokine induction profile implied both cellular and humoral responses, with a more Th-1 favored trend. However, an analysis of specific antibodies against L2 is required to confirm humoral responses. No significant elevation in inflammatory cytokines, (IL-6 and TNF-α), suggested a lack of unwanted inflammatory side effects despite using a combination of two TLR agonists. The designed construct might be capable of inducing adaptive and innate immunity; nevertheless, comprehensive immune tests were not conducted at this stage and will be a matter of future work.