In silico analysis and in vivo assessment of a novel epitope-based vaccine candidate against uropathogenic Escherichia coli.

Uropathogenic Escherichia coli (UPEC) are common pathogens in urinary tract infections (UTIs), which show resistance to antibiotics. Therefore, there is a need for a vaccine to reduce susceptibility to the infection. In the present study, bioinformatics approaches were employed to predict the best B and T-cell epitopes of UPEC virulence proteins to develop a multiepitope vaccine candidate against UPEC. Then, the efficacy of the candidate was studied with and without Freund adjuvant. Using bioinformatics methods, 3 epitope-rich domains of IutA and FimH antigens were selected to construct the fusion. Molecular docking and Molecular dynamics (MD) simulation were employed to investigate in silico interaction between designed vaccine and Toll-like receptor 4 (TLR4). Our results showed that the levels of IgG and IgA antibodies were improved in the serum and mucosal samples of the vaccinated mice, and the IgG responses were maintained for at least 6 months. The fusion protein was also able to enhance the level of cytokines IFN.γ (Th1), IL.4 (Th2), and IL.17. In challenge experiments, all vaccine combinations showed high potency in the protection of the urinary tract even after 6 months post first injection. The present study indicates that the designed candidate is able to evoke strong protective responses which warrant further studies.

Silk Fibroin Nanoadjuvant as a Promising Vaccine Carrier to Deliver the FimH-IutA Antigen for Urinary Tract Infection.

In this study, the silk fibroin nanoparticle (SFNP) was used as a nanoadjuvant in combination with a multiepitope-based vaccine for urinary tract infection (UTI). Nanoparticles containing the fusion protein were analyzed for physicochemical properties, toxicity, release profile, and in vivo potency. The synthesized nanovaccine showed a spherical shape with a mean particle size of 180 nm and an encapsulation efficiency of 88%. Antigen release from SFNPs was 18% after 42 days. The SFNPs showed a zeta potential of -29 mV and had no toxic effect on the L929 cells in vitro. SFNPs in the vaccine formulations promoted humoral and cellular (IFN-γ, IL-4, and IL-17) immune responses in comparison to controls. Immunization of mice with antigen-encapsulated SFNPs significantly increased the total IgG as well as IgG2a/IgG1 ratio. In addition, this formulation triggered concurrently type 1 (Th1) and type 2 (Th2) immune responses, with a Th1-polarized response. Furthermore, highly effective protection of the bladder and kidney against experimental UTI was obtained by using the nanoadjuvant containing the antigen for 6 months. The results demonstrated that SFNPs can be proposed as potent adjuvants or vaccine carriers to develop new and more effective nanovaccine formulations in the future.

Epitope-based immunoinformatics study of a novel Hla-MntC-SACOL0723 fusion protein from Staphylococcus aureus: Induction of multi-pattern immune responses.

Staphylococcus aureus infections are now one of the most common causes of surgical drainage, bacteremia, and hospital-acquired infections. The emergence of antibiotic resistance has increased mortality and costs of treatment. The design of a new vaccine against S. aureus would have a great beneficial impact on public health. In the current report, we design and introduce a novel epitope-based fusion protein (Hla, MntC and SACOL0723) and investigate its biological activities. Three known antigenic proteins from S. aureus were analyzed for the prediction of immunogenic B and T-cell epitopes and validated using bioinformatics tools. The affinity and the map of interactions between the receptor and ligand were evaluated via docking protocols. Functional activity of the recombinant protein was assessed by western blot and opsonophagocytosis tests and determining the bacterial burden from the infected tissues. To determine the type of induced immunity, cytokines profile and isotyping ELISA was performed. Based on in silico analysis, seven epitopes rich domain including highly scored T and B-cell epitopes were selected. The study results indicated that the high titer of specific antibodies raised against the vaccine candidate could opsonize the bacteria and decrease the viable bacterial cells. The fusion protein was able to elicit a mixture of Th1, Th2, and Th17 immune responses more towards Th1 and Th17. In conclusion, the fusion protein formulated with alum could be considered as a potential vaccine candidate for protection against S. aureus in the near future.