Title : Reverse vaccinology-based design of a multi-epitope sub-unit vaccine candidate against leishmaniasis

Objective: The objective of this study is to design a multi-epitope subunit vaccine candidate capable of providing protection against multiple Leishmania species using bioinformatics and immunoinformatics approaches.

Methods: Protein sequences of Leishmania were retrieved from the UniProt and NCBI databases and screened for antigenicity, allergenicity, toxicity, linear B-cell epitopes, helper T-lymphocyte (HTL; CD4+) epitopes, and cytotoxic T-lymphocyte (CTL; CD8+) epitopes using various immunoinformatics tools, including VaxiJen, ABCPred, IEDB, and NetMHCpan. The selected epitopes were assembled into a multi-epitope vaccine construct with suitable adjuvants, linkers, and an additional co-translational residue. The physicochemical properties of the construct and its interactions with Toll-like receptors (TLR4 and TLR9) were further assessed through computational analyses.

Results: The final vaccine construct consisted of 491 amino acids with a molecular weight of 54,080.71 kDa and a theoretical isoelectric point (pI) of 9.27. An instability index of 38.11 indicated that the construct was stable, while a GRAVY score of −0.586 suggested a hydrophilic nature. Molecular docking analysis revealed stable interactions between the vaccine construct and immune receptors TLR4 and TLR9, with binding energies of −281.30 kcal/mol and −320.52 kcal/mol, respectively. The stronger binding affinity observed with TLR9 was indicated by its more negative binding energy. Furthermore, the vaccine candidate was predicted to be non-toxic, non-allergenic, and highly antigenic.

Conclusion: The findings suggest that the designed multi-epitope subunit vaccine possesses favorable physicochemical and immunological properties, including stability, hydrophilicity, safety, and strong antigenic potential. Its predicted ability to interact effectively with immune receptors, particularly TLR9, indicates its potential to stimulate protective immune responses against leishmaniasis. Nevertheless, experimental validation through in vitro and in vivo studies is required to confirm its efficacy and safety.

To be updated shortly..